I have a honda civic 94, ex, I need to check my gas filter , someone told me that might be the reason why it won't start.

<moved to cars & trucks>

More than likely, you have an electrical problem. Reading sections A and B below should help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-46563.html

Here's information on how to replace your fuel filter:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-46563-2.html#post224689