Melon r658 router bricked

i was flash a wrong firmware to my melon r658 router and it's broken.. can't connect to the router ip...i was do a backup in my laptop but don't know how to use it to recover my router back because it's in .tar.gz format.. anyone can help me with this or can anyone tell me which firmware that comfortable to be flash with tftpd to the router.. please help!!!
The router is using mt7620n chipset with usb interface that can connect to usb long range adapter.