why is my 05 monte carlo cranking but dont start

Probably have no spark, check to see if there is spark.

But it recently got a tune up all spark plugs new, wires, oil & filter, and tranny got maintenance

That doesn't stop a component like the coils, or ignition control module to fail, and you have to start somewhere with the diagnosis. Check to see if there is spark.

I was told it does have spark, but maybe fuel filter or pump.

Yes fuel would be the next thing to check, so get some starting fluid and spray a little bit into the throttle body to see if it fires off. If there is not a spark issue, then the engine will run until the starting fluid is burnt up. Then change out the fuel filter, which you probably should anyway, and see if it starts. If not then it is a good indication that the fuel pump is bad, or not working. Also just turn the key to the on position, and listen if you can hear the fuel pump prime up, run and turn off, checking to see if there is power to the fuel pump.