If it was truly a Grade 1 sprain (meaning no ligamentous laxity causing ankle joint instability) then your recovery should be 1 to 3 weeks if you rehab it aggressively during that time.

If it does not return to normal function during that time consider the following factors as causes:
-- Inadequate rest/rehab [most likely]
-- Inaccurate grading of the sprain initially

Straight-line running should only be restarted after you can complete a rehab protocol/physical therapy session with no pain during or afterwards and no swelling/pain the following day.
When you restart running, begin with a reduced total weekly mileage level -- reduced by 50% for the first week.
If ANY pain or swelling occur, stop running and restart the rehab phase again. You can repeat this running trial after a couple more weeks.
If you restart running at 50% and have no adverse effects, the increase by 10% each week until you are eventually back at your usual weekly mileage load.
If repeated running trials fail you need additional evaluation by an orthopedic surgeon or other sports medicine practitioner. You may need more imaging (x-rays or MRI) to evaluate for lingering inflammation in the sprain ligament(s).

You can improve ligament healing by adding the following to your daily routine:
-- Bone broth: the real stuff from bones cooked for days. Check local health foods stores. 1/4 cup per day at least
-- Gotu kola -- an herb that promotes connective tissue healing
-- Ice bath for your ankle -- Not lousy ice packs! Submerge that thing in ice water for 5 minutes once a day.

Good luck!

Loudoun Holistic Health Partners