Spotify application won't close or respond to anything

So basically, for the past two weeks, my Spotify App icon has been open in the dock whilst stating 'Application Not Responding'. I can view it in the Force Quit menu, which I've used multiple times to attempt to Force Quit it, to no luck. I've also restarted my Macbook Pro many times with it still being visible on the dock. I've attempted to view and close it in both Activity Monitor and Terminal through other help topics however it isnt viewable in these applications, i.e. it doesnt show up on the active processes or in Terminal (when commanding top -u etc).

It's very annoying as I cant use spotify now on my macbook since it states that it is already open, and I cant uninstall it as it says the app is active and being used. I've also tried re-installing without uninstalling however it asks to close the original Spotify before attempting to install.

I'm running OS X Yosemite - Version 10.10.5

Macbook Pro 13" (Early 2011)

2.7 GHz Intel Core i7

Please any help would be fantastic!