I'm sorry that you're having a frustrating experience with watching lectures in your course, @RashaHassan. The best person to contact is your instructor to let them know. Then connect with your college's technical support or student services teams to see what help they can offer. Unfortunately in the Instructure Community we won't be able to help with what sounds like a hardware or bandwidth problem.
I’m going to mark this reply as a solution. I realize it does not solve your problem, but our colleagues who have a similar critique will also find the best way to pass on the feedback.