I agree with 300SDLLLL and suspect the light switch also.
Surely you know how to operate your light switch.
So it is not that, we hope.
Disconnect the battery's NEGATIVE cable. It is ALWAYS good practice to disconnect the neg. cable first and re-connect it last. Sheetmetal is negative, so if neg. cable happens to touch, no problem. If pos. is removed first and touches sheetmetal... well... let's just say it's exciting !
