There are a few potential causes for your Amazon account to be locked. If you have not used your account in a certain period of time, or if you have made any changes to your account that are not authorized by Amazon, then your account may be locked. Additionally, if you have been reported as being pirated or selling counterfeit products on Amazon, then your account may be locked. Finally, if you are using an unsupported device or software when logging into your Amazon account, then your account may be locked.