Regarding whether your knee will be amenable to treatment some years after the initial injury, the answer is generally yes, but a repeat assessment will be required to determine what is necessary.
For many patients with an ACL or meniscal injury, surgical intervention is not immediately required and rehabilitation can certainly help.
If you are having ongoing swelling, instability or locking, or your work/sport is significantly impacted, then seeking help would be advisable.
Hope this helps.