Actions just stoped working

The problem:

I have a site which let users post through a formidable pro form, and it was working great until 4 month ago (i only now realized it).

It seems all the forms on the site stoped doing there actions!

The contact us form doesn’t send emails, the post form doesn’t send me emails, doesn’t send the user emails and doesn’t create the post etc.

My research for now:

• The entries are saved in the formidable panel.
• Checked the site mail, and it sends emails (forgot your password and stuff…).
• If i use the “resend mails” from the formidable edit entry screen it does send the mail, but doesn’t create post.
• Also tried to reinstall the formidable plugin. also tried deactivating all other plugins.
• Also tried to switch to one of the WordPress default themes.

This is one of the forms on the site.

*If you need access to the site admin i will send you details. it is very argent because the site is actually not getting new clients for 4 month now (lucky one paypal customer was asking for a refund after trying to contact us a few times through the contact us form).