To get back into your account, log into Facebook and follow the instructions to verify your identity and, if necessary, scan your computer for viruses. If you can't remember your Facebook password you can request a new password.
You may have the option of confirming your identity by:
Identifying friends based on their tagged photos
Answering your security question (if you added one to your account)
Using your trusted contacts (if you added them to your account)
Providing your date of birth
After you complete this process, please be sure to read the information provided regarding keeping your account secure.
There are actually other options aside from confirming your security question.