We are members like yourself, and with no access to your account we can only direct you to your eBay messages regarding this restriction. We cannot advise how to reinstate your account as we do not know why you were restricted sorry.
This describes an MC011 restriction:
Mc011 is one of the most complex restrictions on eBay's system which is imposed due to majorly following scenarios. Multiple cases from buyers that you have not addressed or properly resolved. Low percent of Tracking number uploaded on time that is 60% High returns & cancellations rates may cause MC011 that is 25%.
Your DSR Detailed Seller rating on your Feedback Profile page, will show you any below standard levels which need to be improved on.
Contacting Customer Services is of no use as they do not explain any restriction and they will just direct you to your eBay messages and any suggestions there.
If this is a timed restriction you just have to wait for that time limit to lapse, to be able to sell again. If eBay have infirmed you of a ' permanent' or ' indefinite ' restriction, then I'm afraid this is a lifetime ban, and there's no comeback from that.
@eden_quest