I was cleaning out my old windows 7 HP desktop computer approximately 5 months ago. There was only the expired Norton 360 as far as antivirus and no firewall. Up until this point I disabled the wifi since I knew it was unprotected. I put all of the files I wanted to keep onto two external hard drives. Then I deleted them from the internal hard drive. When I went to find a file on the external hard drive a day later, it wasn't there, so I performed a system restore from a very old back up, and then I downloaded a recovery tool from cnet downloads. My intent was to get all of the files back and repeat the saving. I did that and got some files back, so I just left the program open and the computer on, but in sleep mode. I thought I disabled the wifi connection, its my usual practice to do so, but I admit, I may not have.
Due to work/travel I just left the computer on for like 3 or so months in the sleep state with the program open under my windows user profile. It would occasionally leave sleep mode but the screen would stay off, I could just hear it wake and then sleep, I assumed it was just me stepping too hard and moving the mouse or something like that. When I woke the computer on purpose after all that time, it was open in under my dad's windows user profile, which isn't password protected. I also checked and saw that the wifi was connected.
I live alone, so the odds of someone physically using my computer is ~.001% as I haven't had guests, and nothing was missing and there was no sign of entry. Also on the desktop of my dad's user profile was the verizon fios home manager icon which seemed new, but then again I never was on his profile, but I personally don't remember this being there, and he never used the computer, I just set it up for him.
Was I hacked?
How can I check?
Could someone have accessed my plugged in external hard drive? I had WEP protection on my Fios router. Which I know isn't safe (now). Sorry for the long post. Just wanted to be thorough.
Additional info: I downloaded Avast immediately after I thought something was wrong and I turned on the highest level firewall and disconnected the wifi. I scanned every drive 3 or 4 times and didn't find anything. I then turned the computer off and haven't had it on since. That was approximately a month ago.