If your teeth is not affected upto the pulp, you can have a filling done. Otherwise if the pulp has been affected, you might have to get RCT done. The treatment is absolutely painless and done under local anesthesia.
Next Steps
You can get an x ray done for the involved teeth and consult for further treatment options.
Health Tips
Please do not waste time, and refer your dentist asap.
The earlier the treatment done, the more conservative it would be, ie. you would be able to preserve more tooth structure.
Good luck..