If you don’t have a USB drive, there are still a few ways to install Linux Mint on your computer. Here are some options:
Install through LAN: You can set up a BOOTP + DHCP server and boot over the network via PXE.
Use UNetbootin: You can create a frugal install onto your computer using UNetbootin.
Install directly to the hard drive: You can install Linux Mint directly to the disk if you have a computer that has a DVD drive, you can use it to create a bootable Linux Mint DVD.