DON'T try Easyouts! (A misnamed tool)
Left hand drills MIGHT work, if you have any the right size, otherwise, as JD says try drilling, but try a tapping size drill first, and then clean up the threads. If that fails, as said, drill out and tap next size up (Assumes that there is enough meat left behind the scenes for this)
Maybe applying an anti seize compound when fitting the new screws may help for next time, whenever that may be?
Howard