You haven't said what sort of restriction has been applied, or for what period. As you no longer have any items for sale I imagine it's a restriction from selling.
It's unlikely to be identity fraud. What has almost certainly happened is that eBay has associated your account with one that has been restricted for some form of misconduct. Typically, they could be someone at your address, or who shares the same IP address, or whom you have ever allowed to log in on your connected device - or who has let you log in on theirs.
The bad news is that if the restriction is indefinite, on eBay this means permanent - for life. It will also be applied to anyone else at your address. You can try to contact eBay about it. Good luck, but other sellers have told us they won't even discuss restrictions.
