I was copying the folder Roicoin on a flash pen from appdata-roaming while the wallet was open.. now the wallet says"fatal error" and terminate.
What should I do?

last lines of debug.log:
2018-03-02 11:09:33 ERROR: ReadBlockFromDisk: Errors in block header at CBlockDiskPos(nFile=0, nPos=82774426)
2018-03-02 11:09:33 *** Failed to read block
2018-03-02 11:11:41 scheduler thread interrupt
2018-03-02 11:11:41 Shutdown: In progress...
2018-03-02 11:11:41 StopNode()
2018-03-02 11:11:41 CDBEnv::EnvShutdown: Error -30974 shutting down database environment: DB_RUNRECOVERY: Fatal error, run database recovery
2018-03-02 11:11:41 Shutdown: done
It sounds like you corrupted the blockchain database by attempting to live copy its files while in use.
You likely just need to resync the blockchain ( rebuild the database ), with the same wallet.dat.
IF that still doesn't work, do you have a previous backup of your wallet.dat , try that instead ?
Note: resync means, remove blocks/chainstate subfolder and let the wallet re-download it from the network.
Always, keep backups of your wallet.dat file.
ghobson, thanks very much. I removed blocks/chainstate subfolder and let the wallet re-download it from the network. credit reconfirmed and wallet synced.