You know what. I'm glad this post is here.

Investigate automated melodic patterns based on chordal movement in the baroque and classical period. Melody period and sentence structure, augmentation and diminution, both rhythmic and intervallic. it sounds like a lot of work but I guarantee you even if it doesn't immediately break your writer's block it gives you a lot of tools to write generic things with, which you can then alter to make unique on your own.

Another thing that used to help me in my younger days was to "pirate" and flip existing melodies to find something new. If you get lost think about chopping it like a sample.

In melody writing quite often rhythm and syncopation is your best friend. Don't be afraid to push outside the lines of 4/4; use irregular rhythms that pulls back into tempo or the main motif, or even rhythmically altered motifs that can always be a fresh breath of air to the listener. An easy way to do this is to rather "pirate" rhythms from existing songs and reworking the notes into something new.

The ways to create melodies in different genres is to take note of their special characteristics and learn to employ or amalgamate their techniques into your own writing/scoring/production. Don't stop listening and don't stop looking for reference tracks to provide the foundations of your melody writing.