1997 Buick Skylark Fuel issue?

The car started up and ran anytime I needed it to even after sitting for almost a year, until some young punk who was interested in purchasing the car started messing around with it! The car will turn over but it wont start acts like its not getting gas can't find the location of fuel pump fuse nor the relay and wonder if there is a shut off switch like Ford has for safety and its location (can't find anything in owners manual or the chiltons manual for this vehicle) Also the check engine light and traction control light has been on some time and the wrong gas cap is on it but the car ran fine with these things. There is a small pinhole leak in heater core which leaks to outside but was fixed with stop leak at a shop about a year ago, it seems to need it again. The new light that is on says security system (thought that only was for radio but maybe not?) And the gas gauage says full tank even though it was drained of gas. The gauge jumped down to about 3/4 mark but quickly back up to full when key was turned on. I put about six gallons of gas and some gasline antifreeze in it after I attempted to start it assuming it still had gas in it per gauge but it still wouldn't start nor did gas gauge move. It will start with Starting fluid. This kid did empty the gas out of tank this summer (I think he may have removed a line and turned on key to let fuel pump pump it out?) but had car running and drove it short distances several times after that. He also put gas treatment in oil res but I made him drain and change oil & filter after that but he left cap of oil res for about two months (discovered when discovered he put water in radiator and vehicle froze (not solid but very close) I immediately put heat (lights) on car motor and disconnected bottom radiator hose going to block to let water drain and added new coolant befor attempting to start car. It wouldn't start, also put heat back by gas tank and lines in case they were frozen too but still wont start except with starting fluid. cant tell if fuel pump is working or not, never could hear it before, want to first check fuses/relays but can't locate as I stated earlier. Any other suggestions based on the other stuff done to car? I am disabled single mom, daughters only vehicle developed big problems, she is full time student and works full time, so we need this car to work as I have daily therapy to attend!!!
ps car does have spark checked that first!

updated 11/22/08
Is it something on the key that makes the anti theft system turn off or how do I get it to reverse or come out of long term theft mode?