I can't get into my gmail. My Google gmail icon disappeared a few days ago. I have had to go into the Firefox icon. I now made Firefox my browser. I still can't get into my gmail. Please help, NOW!!!!!!!

I can't get into my gmail My gmail icon disappeared from my icons screen a few days ago. I had to get into my email by going into Firefox. Now that isn't working either. I decided to make Firefox my browser, so I did that. Now what do I do? I still can't get into my gmail!!!!!!! Please help!!!!!! NOW