The most common reason Apple IDs get disabled is because of the wrong password being entered too many times.
First, try going to https://appleid.apple.com/#!&page=signin and clicking on the "forgot Apple ID or password" link in the middle of the page (it's small print, so look carefully). Go through the steps there, which will require you to provide your email address, and you should be able to reset it.
You can also go to https://getsupport.apple.com/ then click on "Apple ID" and then "Disabled Apple ID." This will give you some other options including scheduling a call to talk to Apple support.
It shouldn't be too much of a problem to get this resolved.
If that doesn't work, the best bet is to just give Apple a call.