Hi i have shooting pain in my knee what could it be sprain torn muscle ligament ect and what should i do i also. sometimes can't walk on it thank you.

Modify activity: It could be a number of different things depending upon your activity level and whether or not there was any specific event that preceded it. Is the knee swollen or unstable when walking? Your symptoms should improve over several days to weeks with rest and eliminating any activity that could worsen it. If not, it is worth getting evaluated by your primary care physician.