Correct password for windows 7 Home Premium not working anymore?

A couple of weeks ago the correct password for my PC stopped working and I have no idea why. I have tried many times the correct password (oh trust me it is not a matter of caplocks) and it does not work. I have alot of files on the PC that i really need (pics of vacations, Uni files, music etc).
My laptop is a HP Pavilion g6-2235tx
I dont know if this would be helpful but, whenever I go into the login window the window that appears when you hold down shift for too long appears.

Thanks in advance for any help.

I was unable to type certain capital letters using shift and was even locked out of windows because of being unable to type a capital A. I had just recently uninstalled Amd graphics driver and couldn't think of how the two would be related. They weren't. I remembered my ~ key had been getting stuck periodically and checked on it. I noticed it was stuck and and I pried it up with a paper and tried again.

I am very glad to say that this instantly fixed it and I could now use shift with all letters to type their capital forms. If you are also having issues typing certain letters with shift then I recommend checking if ~ is stuck or use the on-board keyboard to type the letters. If your windows password is not working and you know that it is correct also check for these issues because it could be an issue of typing the capital letters used in your password.

I really hope this helps because it has happened over 4-5 times now. Twice I was locked out of windows and didn't realize it was because I was unable to type capital letters until now. Also, do you notice many people say it randomly resolved itself? It may be because their ~ key was stuck and unstuck itself or they unstuck it without putting the two together. How many times do you have a stuck key and just pop it up without thinking about it? Good luck and I'm hoping now I will never have this problem again.