What can run but never walks,
has a mouth but never talks,
has a head but never weeps,
has a bed but never sleeps?

(In reply to answer by K Sengupta)

Since the referred to person/object can run but is unable to walk, it is clear that we are looking either for an inanimate object or a natural phenomenon or natural formation or  manifestation of a natural phenomenon.

The word "run" in conjunction with "bed", "head" and "mouth" suggests "river" as a possible answer to the riddle.

This is corroborated in terms of the following definitions:

RiverMouth:

Definition: RiverMouth is the subclass of WaterAreas that are the outfalls of a river or stream into another body of water

Source:
http://sigma.ontologyportal.org:4010/sigma/Browse.jsp?kb=SUMO&term=RiverMouth

Riverbed:

Definition (i): The area between the banks of a river ordinarily covered by water

Definition (ii):  A channel occupied (or formerly occupied) by a river

Definition (iii): The passage where the river flows is called the riverbed

Sources:

http://www.answers.com/topic/riverbed?cat=technology

http://simple.wikipedia.org/wiki/River

Riverhead:

Definition:  The source of a river.

Source:
http://www.answers.com/topic/riverhead

In view of the foregoing, it is now clear that the required answer to the riddle is  "River". 

Edited on April 18, 2008, 7:12 am

Posted by K Sengupta on 2008-04-17 12:22:32