I have a civic 98 dx manual transmission as driving my car shutoff nd crank it again nd restarted but then after it completely turnoff and wouldn't start again what might be the problem?

Check for spark first from the distributor to the engine: Remove any of the 4 spark plug cable (just one) put it near a propper ground (the inner part of the cable very close to an engine ground) ask a friend to start the engine as he tryes to start you must see sparks jumping from the cable to the engine or chassis ground. (Before you do this, remember to hold the cable with some plastic pliers that way the current won't hit you). If there is spark coming out of the cable the you have ignition and the problem could be that you have fuel issues. To try this, remove the hose that is going to the fuel rail (going in, not the return line), grab an empty coke bottle and put the hose inside the bottle, ask a friend to put ignition switch on, you should see a lot of fuel coming from the hose to the bottle, remove ignition switch and reconnect hose. If there is fuel and spark you have ignition, but in your case one of them will not be present. Hope this helps, if not leave me a message to see what else can we check.