You're shadowbanned.

The only thing that you can do is to message the admins using your shadowbanned account and patiently wait for a response.

Politely ask them why you were shadowbanned. They don't always respond to the first message so be mildly persistent but don't message them more than once a day.

Read up on possible rules you may have violated: http://www.reddit.com/rules. Read them all and click every link.

The details of some are not as obvious as others.

Some bans are done by mistake, but if you know you broke a rule, be honest and apologize. Your activity, including PMs, private subreddits, alt accounts and voting history are utterly transparent to them.

I AM A BOT, however real people will be along to answer any remaining questions so feel free to leave a comment anyway.

If you do have success getting your account back in good standing, the guy who wrote this would really like it if you reply to this thread letting him know that it helped. Good luck.

/r/Shadowban Copypasta version 2.3.1