Put in password 3 times then laptop locked up. All I get is a blank screen with the cursor in the top left hand side.

Try starting it in safe mode, right after you turn it on you will se option like esc, f1 and f10 at the bottom of the screen, press the f8 key and a menu will display, use arrow keys to go down to safe mode option then press enter, do it quick, you only have 25 seconds to do it before computer starts normally, you wont see the f8 option but you have to press it, if it doesn't work, try keeping it pressed till menu shows...