A have a Toyota Tercel and it running but it got a knock on the engine now what could be the problem?

A knocking sound in your Toyota Tercel's engine could indicate several issues, such as low oil levels, worn bearings, or detonation (knocking) due to poor fuel quality. It may also be a sign of engine wear or damage, such as a failing piston or connecting rod. It's important to check the oil level and quality first, and if the knocking persists, have a mechanic diagnose the problem to prevent further damage.