This is how I solved the cron issue:

1. Via PhpMyAdmin I looked in the semaphore table and deleted row where name = cron.

2. I ran "drush cron" via command line

3. I seen an error message that gave me a clue of the issue. This may be different for you but for me a recently uninstalled module was sharing a php library with an installed module was causing this error.

This is how I solved the cron issue:

1. Via PhpMyAdmin, I looked in the semaphore table and deleted row where name = cron
2. I ran "drush cron" via command line
3. I seen an error message that gave me a clue of the issue; this may be different for you, but for me a recently uninstalled module that was sharing a PHP library with an installed module was causing an error