I too have a dream of finding a composer to work with my lyrics.However, while I wait for such a person, I have learned some tricks for getting a passable and original tune, if not always inspired.
I pick a melody that belongs to a song I already know with the same emotional content as the song I am developing. Then I start changing it until the melody is something new.
Here are some of the ways you can change it:
* Go up where the melody goes down or vice versa
* Throw some random note, interval or chord in an unexpected place in the melody.
* Change the length of a phrase by adding or subtracting something.
* Modulate to another key for a line or two.
Remember also that in folk music it is a time honored custom to put new words to an old melody, sometimes as a parody and sometimes as a wholy new song. Woody Guthrie did it all the time.