i replaced a gas tank on a 1994 chevy blazer s10 4x4 thefuel pump work, i also changed the spark plugs and wires and the fuel filter the blazer wont start but tries to turn over what else should i check?

Is that the only gas tank? And make sure you have enough gas in it. Could be water in gas too! Check the battery for a full charge and terminals for corrosion or loose connections. Or vent lines could be clogged. And you didn't mention if carbed or fuel injected? So will assume a carb and possibly a faulty distributor(if equipped)components and check the cap. What else, low cylinder compression, wet or damaged ignition components, incorrectly gapped plugs. (I recomend replacement of original type and specs only). Broken, loose or disconnected wires in ignition circuit or at ignition coils. Or faulty coils, timing chain failure or wear affecting valve timing. Lastly, areas of starter. Good luck you have so many possibilities.

considering its a 94 its likely to be fuel injected if this is the case run a code search on it to see if any emission control codes come up, if so its likely going to be in the intake manifold. I had this same issue on a 96 and had to replace the manifold for a pricey $800, I no longer have it due to the fact it did it again. Never could track down as to why these models have this problem.

does it have spider injector pump or throttle body if it has spider injector make sure you have minium of 65 lbs of fuel pressure. If it throttle body it has to have a minium of 40 lbs fuel pressure. first need to know why you replaced the fuel tank and what it came out of or is it new.

has the fuel pressure been checked

Do you have spark at the plugs?
Fuel at the Throttle body?