There are a few different ways to activate a restore point, depending on your operating system.
For Windows XP, open System Properties, and select the System Restore tab. Then, check the box next to "Turn off System Restore on all drives." Click Apply, and then click OK.
For Windows Vista, open System Properties, and select the System Protection tab. Under Protection Settings, select the drive you want to turn off protection for, and then click Configure. Select the Disable system protection option, and then click OK.
For Windows 7, open System Properties, and select the System Protection tab. Under Protection Settings, select the drive you want to turn off protection for, and then click Configure. Select the Turn off system protection option, and then click OK.
For Windows 8, open File History, and then click the Turn off button.
For Windows 10, open Control Panel, and then click Recovery. Under Advanced startup, click Restart now. Then, click Troubleshoot, and then click Advanced options. Finally, click System Restore, and follow the prompts to activate a restore point.