99 cav overheating, now wont start

im going to replace the thermostat, but i dont know why it wont start. i have gas in the car im getting spark through all wires. im thinking the head gasket may have been blown but it hasnt showed many signs of that other than the overheating i guess... would htat keep me from starting it? i don't have a compression tester.. how can i check tio fuel pump/fuses/sending unit/ or anyhting else i may need to check?

1 backyard way of checking compression is to remove the spark plugs, plug 1 hole with your finger and turn the crank by hand. It is not very accurate but you will be able to tell if there is some compression or not