My blog CRASHED!! help needed!

I was installing a feature post plugin yesterday night. I’ve installed it, activate it tested it. I works fine, but i’ve removed the code from the website, as it didn’t look good so i decided i would do it in the morning. When i got up my site was acting all stupid.
Firstly my feed looks completely awkward and subscribers can’t read anything, nor subscribe: https://feeds.feedburner.com/zmemusic.

Also i can not login or regsiter, as a blank screen appears in my browser after i click login or register ( click here and try to register: https://www.zmemusic.com/wp-login.php?action=register it won’t work so submit any email ). This is very annoying and i have to get this fixed ASAP. Please help me! Thanks in advance.