Severe pain on top of left foot can barely bend toes.absolutely no injuries to foot.do not know what to do.

If: Any redness or infection see an md. May be strain rest ace bandage and may take NSAIDs for 2 wks

Foot pain: See your doctor and get a x-ray done. Sometimnes even a trivial trauma may cause fracture or it is just and a sprain or inflammation of a tendon.

Exam/xray: stress fracture, ligament injury, spasm, diabetic neuropathy, are a few of the conditions all treatable cannot say in your particular case, but generally, rest and anti-inflammatories if they don't help in 24 hrs, you need specific treatment.

Stop Bending: There is only so many things on the top of the foot that when sick, will restrict your toes from bending. I am betting on the tendons and the tissue immediately around the tendons. When this tissue becomes inflamed, The tendons have a hard time trying to slide and glide. The pain is a good indicator that the body wants you to stop using the toes. Elevate , heat /ice, anti-inflammatories and rest.