If you are using an external device, such as speakers or headphones, check to make sure the cables are in good working order and connected to the proper audio port on your computer. If your speakers require a power source, make sure they are plugged into an electrical outlet and/or AC adapter. If you are using external speakers or headphones that have an independent volume, make sure the volume is turned up and that the "Mute" button is not engaged. You can also use the following steps to check the volume on your Windows computer: Click the Windows Start icon in the taskbar. Type "Adjust volume." Click Adjust Volume. Use the slider bar below "Change device volume" to adjust the volume on your computer. Check to see if you are having volume problems on all apps, or just one specific app. If you are experiencing volume problems on just one app, the problem may be with the sound settings for that app. For example, Spotify has a volume slider bar in the lower-right corner of the desktop app. You can also adjust the volume on YouTube videos by clicking the speaker icon and adjust the slider bar. Games may have their own sound and volume settings in the Settings or Options menu. Windows computers come with built-in troubleshooter app that can help you fix volume issues. The Troubleshooter will ask you a series of questions that will help the troubleshooter determine the cause of your volume issue. It may also ask you to open specific settings and suggest that you make changes to the settings. Use the following steps to open the Windows troubleshooter: Click on the Windows Start icon in the taskbar. Type "Troubleshoot Settings". Click Troubleshoot Settings. Scroll down and click Playing Audio. Click Run the Troubleshooter. Follow the instructions in the window. If the sound is not playing from your computer, this may be because the wrong playback device is selected. For example, if the computer is set to play sound through headphones, sound may not come out of external speakers. Use the following steps to see what playback device is selected: Click the Windows Start icon in the taskbar. Type "Control Panel". Click Control Panel. Click Hardware and Sound. Click Manage Audio Devices. Click the correct audio device. Click Apply. You can also right-click on an audio device and click Test to test the audio device. Most modern computers have a built-in Realtek sound chip used to process audio. However, some older computers may use a third-party sound card to process audio. If your computer speakers plug in to a sound card on the back of your computer, you may need to open your computer and make sure the sound is installed properly. Use the following steps to make sure a sound card is connected to your computer: Click the Windows Start icon in the taskbar. Type "Device Manager." Click Device Manager. Double-click Sound, video and game controllers. Check to make sure an audio device is listed below "Sound, video and game controllers." Sometimes, your audio drivers may be out-of-date and causing problems on your computer. Use the following steps to check for Windows updates: Click the Windows Start icon in the taskbar. Type "Check for updates" Click Check for updates in the Start menu. Click Check for updates in the Windows update menu. Click Download and install now. If you are using a third-party sound card, you may need to install the drivers for your sound card. The sound card should have come with a CD that you can use to install the drivers for your sound card. If you do not have the CD, you can check the manufacturer's website for a download of the audio drivers. Download and install the audio drivers for your sound card.
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One-sentence summary -- Check the cables. Check the volume. Check the sound and volume settings on individual applications. Use a troubleshooter. See what playback device is selected. Check the sound card. Check for updates. Install drivers for your audio device.

While Emerald is sorely lacking in the Eevee department, FireRed and LeafGreen both have a way you can get the Pokemon. If you want to get Eevee without resorting to cheating, you'll need to start a game of either and get at least as far as Celadon City. It's important to keep in mind you'll need to have collected at least 60 Pokemon and completed the Sevii Islands sidequest to open up trading. Once you've opened up the possibility for the Trade Centre, it's time to find Eevee. Eevee may be found in the Pokemon Mansion in Celadon City. Go to Celadon City, and enter the mansion via the backdoor. Get to the roof; on the roof, you'll find a room. Inside, you'll find Eevee's Pokeball. In order to trade, you'll need too Game Boy Advances, a copy of Emerald and FireRed or LeafGreen, and a game link cable to join the two. Get it all plugged in before you try to access the Trade Center. Ask a friend to borrow his Game Boy Advance; this will save you having to purchase another console in order to make the trade. With the two devices hooked up, you can now head to Vermillion City and access the Trading Center. Go up to the desk and speak to the hostess. From there, you can access the trade panel. Ensure the game link cable is joining the two consoles safely, then proceed to make the trade. The data will be erased on the LeafGreen/FireRed game, and copied onto Emerald. Now that you've made the trade, it's always good form to look on your Emerald file and make sure the file has gone through. If the trade has been made, you should see a little Eevee smiling back at you! If for some reason the Eevee isn't there, it's quite possible the trade wasn't completed. It's highly unlikely that one game would erase it without copying on the other, so try again and you should be able to get it down right.
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One-sentence summary --
Start a game of Pokemon FireRed or LeafGreen. Find the Eevee Pokeball in the Pokemon Mansion. Link up two Game Boy Advances. Go to the Vermillion City Trading Center. Make the trade. Verify on Emerald that the trade has gone through.