Your reports are suggestive of a complete ACL tear. Because you're young and active, I'd recommend an Arthroscopic ACL reconstruction surgery along with a meniscal repair/menisectomy. Irrespective of whether you're into sports or not, to prevent future damage to the knee joint, go for the surgery.
Next Steps
-Quadriceps strengthening exercises
-Hamstring strengthening exercises
Please start these exercises as early as possible to prevent muscle wasting. This will also help you post surgery.
Health Tips
Avoid running, lifting heavy objects, jumping as these activities may lead to damage to other structures in the knee