HELP! I HAVE NO FOLLICLES!

HELP!!! Please can anyone explain what might be the reason why I have no follicles at all on cycle day 9 even after taking a combination of 200mg of Clomid and 5mg of Letrozole to make me ovulate! What is wrong with my body? And what do I need to do to finally get the drugs to work for me like it used to because I have a Son whom I conceived with 100mg of Clomid and 5mg of letrozole. Please if this has ever happened to you, I look forward to your replies