Hang on, the very first line: you bought some but the company disappeared? You mean you paid some kind of exchange but didn't bring it to your own wallet, just left it in an account? That probably means no eth was actually yours in the first place, they just had a bookkeeping entry that you owned a share of the exchange's holding. But when the exchange goes defunct, the exchange's holdings are just gone and no blokes from government agencies can get it back.
Hang on, the very first line: you bought some but the company disappeared? You mean you paid some kind of exchange but didn't bring it to your own wallet, just left it in an account? That probably means no eth was actually yours in the first place, they just had a bookkeeping entry that you owned a share of the exchange's holding. But when the exchange goes defunct, the exchange's holdings are just gone and no blokes from government agencies can get it back.