How to fix my computer?

ok this is my second computer, this one is working obviously i'm online, but anyways my gf did something really dumb on my first computer, The first computer was working fine until she stuck her flash drive into the USB port, apparently she saved a file to Open Office Writer, then to her flash drive, but the file that she saved on the computer, I can't find it and delete it and when the computer starts up, something pops up saying Windows Explorer has encountered a problem and needs to close, and says something about DEP (Data Execution Program) the error reports took me to a Temp Folder on the computer listing the files, I attempted to delete the files that were on the error report and new files are beginning to show up so I turned it off, I have three questions, Is it the file on the flash drive that caused it? Is It possible for me to fix it? and How do I fix it? someone please tell me how to fix it step by step, it would be appreciated, right now the computer is turned off while it is still working. One more thing whenever I clicked debug the computer would not restart however it would make the icons go away and then they come back like 3 minutes later and then my computer is working again, The computer does not have Internet Access, so unfortunately it is not up to date at the moment, and if I took it to a computer place, how much would it cost to fix this problem?