hi mohammed,

Firstly, don't be afraid of the exam. Ask some senior who are great in academics for advice. Don't as from seniors who themselves got barely passed in this subject.

Analyze previous year papers of engineering mechanics, see what is important and if something is similar in all the exams. You need practice in engineering mechanics, that means you can't leave this subject just for a day before exam. You will surely fail. You may be not good with mechanics from your 12th. Its okay you can learn now, go to the teacher's staff room if you have some problem. Go even if your friends is not going with you to the teacher for doubt clearing. You have given internals only as of now. External exam have a good amount of weightage, if you study hard you can pass easily after getting good marks in external. As of now, in quarantine try to read from books, youtube etc.

I hope this answer will help.
All the best for the future!!