How do I fix the roof leak on my old house?

Question:It damaged the ceiling in one of the bedrooms..

Answers:
Inspect the roof to see if you can find the bad spot. Apply roof coatings, or plastic roof cement to defect. If you can't see a defect, if you have attic access, you can sometimes see where the leak is by wet or discolored wood on the rafters or the back side of the roof deck. If it's not easily found have someone who has experience find it. Many times the leak is far from the point of drip. It may be another source such as leaking pipes. Having someone repair it will probably be cheaper than replacing fallen in ceilings. And a lot cleaner.