1990 Nissan Sentra will not start

Check for power on the + side of the coil with the key on Then using a test light check for a "pulse" on the negative side of the coil by attaching the clamp side of the test light to ground and the point to the negative side of the coil while cranking. If there is no pulse then it most likely needs a distributor. If there is a pulse but no spark then it needs a coil.

The pop may have been a fuse and needs to be replaced.

good day Sir, try to check the spark plugs and the coil hope this will help you.

Battery MUST be tested to be SURE OF IT after that Go to Starter, Solidoid is Part of the Starter and Is Normal to Replace as a PAIR

do you change the engine oil your car crosses the maximum miles with the old engine oil once your engine oil density become very low you will get the black smoke (or) you need to check the radiator water wether water and coolant is in correct level or not if it is in correct level you need to change the oil

maybe weak or bad starter soilenoid

sounds like a case of closing the horse after the barn ran away...Pretty good chance that you have lost an engine bearing (yes, that means it's new engine time)
To avoid this in the future regard your oil light as a "you just blew your engine" light. Check your oil at least every two weeks, and this will never happen again (not for lack of oil anyway!!!)

It seems you have a timing problem. Have the engine timed properly. If that does not work it could be a craked rotor or distributor cap. have all these checked.

good day Sir, try to check the ignition coil and spark plugs i hope this tips will help you.