I can't sign into my fb page. I am on my Daughter's computer & got on yesterday

Are you sure you're typing your account information in correctly? Double-check that the Caps Lock key is not active. When you were last on your daughter's computer, did you sign out before closing the web browser? Have you run a virus/spyware scan recently with an updated antivirus/antispyware program?
There are 3 possible reasons why you cannot log into your facebook page- 1) Something is causing you to not type your account information into facebook correctly. 2) Someone else got onto your daughter's computer after you used it, and if you left yourself logged in, changed your password. 3) A malicious program or hacker has changed your facebook password information, so they may use it for their own purposes.
For all three, I would recommend these steps: first, try typing in your facebook account information again, being meticulously careful to input your information in correctly. double and triple-check the caps lock key. second, run a virus scan on your computer with updated antivirus software. third, after a failed attempt to imput your account information, beneath the text box where you would normally imput your password, there will be an option saying "Forgot your Password?" in small text. This will lead you to a page where you must answer the security questions you entered when you set up the account- but once answered correctly, will allow you to reset your password.
Have a good day, hope this helps!