i got a 1999 bonneville i have had no problems out of it till now i went to fill up the tank and when i turned the key i got nothing. all guages and dash lights work but starter does not inguage replaced the ingishion stwitch but still nothing can use some help

Check the voltage at the battery both with key off and while attempting to crank. It might be dropping to low when you try to crank.

Clean up the battery cables. A common problem. Both ends of both cables.

ok allready done that not trying to be funny but im no dummy i started with all the simple stuff i could thank of checked all wires all fuses even when i try to tap starter it will inguage but will not kick over and when it does only will run for about 2 seconds. all tho i noticed my oil guage is all the way down not moving. will that make the starter not inguage or car not stay running. ps. i checked dipstick for oil and readings are all good has plenty im stumped

Test the battery cable. Some times they corroded inside. Check in tech info under testing. Choose the index and you can pick the test you want. You will find tests for the cables. There'* also a ground wire on the rear side of the block that provides ground for the sensors. Check that one as well.