Problems regarding Gmail and Play Store apps. NEED HELP.

Hey guys, I hope the geniuses here can help me out with my problem. Simply out, I can't open the Play Store on my phone, it merely shows me the loading screen and the words 'No Connection: Retry' and when I hit retry, it shows the loading screen once more and the same message over and over again. This I partially solved by going to the website, but I find it very inconvenient, as I'm sure you understand. I first realised this when I noticed that my Whatsapp couldn't download pictures that were sent to me, and I thought there must be an update and yeah, I couldn't open the Play Store at all. And my Gmail app, well I'm not receiving any emails at all. I first noticed this when I wa sending an email to the Whatsapp support team about my problem. The email simply wouldn't send, and I wouldn't receive any emails. Please help? I'm getting fed up with my phone because of these things.

And oh, my Whatsapp still can't download pictures sent to me. Any idea what's wrong here? Three apps stop working on my phone? Is it something wrong with the apps or my phone?