Airbag sensor
 

I removed the screws from the front bumper a month ago because we were going to remove it but we didn't so i put them back in. Since then the airbag light goes on and off. How do I fix it?

The light goes on because the computer has stored an error code or codes. The first thing to do is connect a code reader capable of reading air bag codes and find out what those error codes are. It may or may not be related to what you did with the bumper, but nobody here can know that without you getting the error codes read. Once you have them you can go from there.