Regards weights, find out why your hamstring pulled and what function of your hamstring it affects. I pulled my hamstrings 5 times and every time it only affected knee flexion. This meant I could squat heavy without causing any problems but I could not do hamstring curls. My hamstrings pulled due to neural tension steming from the low back and it manifested in the swing phase of the sprint when the leg is out in front. This scenario is not uncommon in sprinters. It took me 10 years to fully appreciate this issue which is why it kept happening.
However this may not be you, your hamstring may be affecting hip extension which means you certainly can NOT squat and you will have to progress slowly into lower body work.
Finding a great physio in the first instance is vital to lessen the chance of reocurrence.