I continually forget my password to log in so PC becomes locked. So I took it to Best Buy for a geek to fix. It was restored in 15 min. with a disc of some kind. Then of course I forgot the password again about a month later. Took it in for another restoration, another geek. He says he can't get into the PC (why doesn't he use the disk like the other one did?) BUT he says there is another way to get in. I don't know that much about computers but I assume he means opening the tower and extracting from the hard drive. Is that right? Anyway, in doing that, will they be able to see EVERYTHING on my hard drive?

He should be able to get password without opening Computer. Did you set a BIOS Password?
You should write your password under you desk, your door jamb, somewhere you don't have to worry about forgetting.
Or write down a word close to your password, enough for you to remember, but not enough for someone to figure out? Good Luck.
Maybe have them do in front of you, so they don't get private/personal data.