• Your location is a factor. Some countries (like China and Iran) ban Facebook
• You cannot get on Facebook
if you are using a connection from school, and if you try to use a proxy site, your school can detect that and they will immediately block the proxy site too.
• Your account may have been suspended for breaking the rules, like using a fake name, lying about your age (you have to be at least 13), or you were adding people you don't know in real life, or you created more than one account. All of those things are grounds for suspension.
• Your account may have been suspended for using a temporary/fake email address. If you did not want to use your real email account for some reason, and created a free yahoo/gmail/hotmail account to use only for Facebook, there is one thing you have to remember. If you do not log in to that email account every 30 days, the email provider will terminate your account.
Facebook periodically checks to see if everyone's email account is still active, and if it's not, they will suspend your Facebook account. The reason for this is people who create fake/multiple accounts often exhibit this behavior, and another reason is that spammers do the same thing. Facebook does not tolerate this type of usage, and you will not get a warning before your account is suspended.
• You were tricked into installing a browser extension or an app that is using your account to spam and Facebook
detected it and disabled your account until you fix your computer/device.
• You are using IE and hackers have found yet another IE exploit. I use Firefox as my browser (Facebook
is working just fine for me, and I also use ADBLOCK PLUS to hide the advertising, which can sometimes be malicious. Never use the internet without anti-virus AND anti-malware protection.
• You used a proxy site at some point, which means the owner of the proxy site now has your email/password and is logging into your account in order to spam your friends to make money.
• You gave your password to someone else, like your parents or your friends or your boyfriend/girlfriend, not realizing that is against the rules and grounds for suspension.