94 civic ex wont engage into gears?

It may be due to hydraulic or electrical problems rather than the gears themselves. The transmission will not operate properly without the correct amount of fluid because it uses it for hydraulic power and lubrication. Check the transmission fluid level in the engine compartment and fill the transmission fluid if it reads low. Undo the clip on the wiring harness and unseat the ECU from its bracket with your hands. The ECU controls the operation of the engine and can be faulty. It may be stuck in "Fail-Safe" mode which would not allow the vehicle to shift gears. Take the ECU to a professional to run a diagnostic. Remove the speed sensor and unfasten the wiring harness on the sensor with your fingers. The speed sensor is a small electronic plug with three wires coming from it. Install a new speed sensor by clipping the wiring harness into place and using a 10-mm socket to screw the sensor into its splined hole. The speed sensor sends electronic information to the ECU so the transmission may operate. If no information is sent, then the transmission will fail to operate. Hope this helps.

Trans wasnt done right,,you should have a guarantee for anything rebuilt just in case of problems like this. Take it back to the shop and tell them your problem,,they should look at it and fix any problem at no cost to you....if they had a guarantee/warranty

is it a automatic or manual??