You'll probably need to get onto whatever e-mail your battle.net account is linked to. There should be a message from Blizzard listing the details and what you need to do in order to fix it. Here's the key wording you're looking for in the message; locked means it's a minor issue, which can be fixed very quickly and easily (like if you logged onto your account from a computer you don't normally use (yes, Blizzard is now checking the IP address for every login to see if it matches the one or few you normally use)), suspended is a bit of an issue, but so long as you actually didn't do anything wrong and send a reply to their customer support team explaining what happened, you should be good fairly soon (a couple days at most), but if it actually says BANNED and you really are innocent, it's still gonna be a pain. If the worst happens, perform virus/malware checks on your computer, remove any that show up, change the password for the e-mail (and do a few other safety precautions), then contact the customer support team ASAP to explain your situation. At that point, they will put your account in a que (keep in mind this happens to a ton of people) in order to verify that you are innocent and hacked by a third party, but this can take anywhere from a few days, to even a few weeks depending on the severity and your number in que. When and if you get back on, if you are noticeably missing items of value, you will need to contact a GM via the in-game help to speak with them in order to get those objects back, but this will add a few more days in order to complete.
I know it's rough (been through the first and third experiences myself), but don't let it get you down. Hopefully, it's just a minor issue, but best of luck if it isn't. For the glory of the Alliance! And if you are Horde, may we meet in honorable combat one day!
