Did a system restore on a Toshiba laptop, now Windows 7 won't start

I recently bought a Toshiba laptop from my friend, who bought it brand new on Christmas. The computer originally came with Windows 8 but his brother apparently installed Windows 7 early on. When I bought the computer I noticed it was a little slow and cluttered with my friends files (but otherwise ran fine), so I decided to do a system restore. To ensure that all junk was deleted, I chose the earliest system restore point. Now whenever the computer starts, it freezes on the Starting Windows screen. I've tried booting in Safe Mode, low-res, nothing seems to work. I've also tried many of the solutions in Startup Repair including a system restore to a later point than what I had selected previously, did a memory scan, and pretty much everything else in that Startup Repair menu and nothing seems to be giving me any luck. Since I bought this computer used, I don't have a Windows 7 installation disc. The only way I can think to do a fresh install of Windows 7 would be with my USB external hard drive, putting a bootable install of Windows 7 on the drive with another computer. Anyone know how I could do this? Or have any other suggestions as to how I could get my computer working again?

Is there any way I can do it with a bigger USB drive? The only one I have is 500gb.