Unable to open passenger door from inside the car

Has anyone had this problem? I am unable to open the passenger door from inside the car. The only solution so far has been to lower the window and reach out to the door handle, or walk around to the passenger side and open it. The problem started after a period of heavy rain which caused a build up of water in the door. It seems that some leaves had blocked the drain holes in the bottom of the door. Once cleared, the water was released. Could water have entered the mechanism and caused the problem?
Hopefully someone will have a solution! Thanks in advance.