It sounds as though the socket needs replacing. There is obviously a fault in the internal connectors. This isn't some thing that you can repair.
Bin it and get a new one - or better still, get a qualified electrician on the job.
Given the thick copper connection betwen the two that sounds an unusal thing to have happened, but if they each have their own switch, it is there the problem probably lies. One switch isn't making contact.
As MichaelZZ says, these things are not repairable, replace & sling into the recycling or waste bin.