AMD Radeon R5 M335 not working on Inpiron 5559 (win8.1 64-bit)

You can't run the AMD GPU independently of the Intel GPU - the AMD GPU is just a co-processor.

Does the system recognize and have drivers loaded for BOTH GPUs?  If so, are you using the AMD Control Panel (or context menu) to choose the AMD GPU for the applications you want to run with it?

The AMD GPU depends on the Intel GPU to function - and there are often settings that need to be changed for certain games (and in fact there are still plenty of games, many older ones, that will not run with a hybrid GPU setup).

I don't know if it recognizes the drivers for the AMD,but yes,they are visible in the device manager menu..And yes I am using the context menu and have those games that I am talking about put on high performance.

The game isn't that old (2013) and it's an online game that gets updated ~every 3 weeks so I doubt the system remained the same for the game throughout the years,Problem is,when I disabled the AMD drivers from the device manager menu,It didn't change the FPS at all,it didn't decrease as it should've if the AMD GPU was boosting my FPS in the slightest bit.

Your best bet is to contact the game publisher for their recommendations on hybrid video settings.

Also realize that this is a relatively low performance AMD GPU - it's designed for multimedia work, not really for any performance-required gaming.  You may see 10-15% better results than using the intel GPU alone, but you're not going to get barnstorming performance out of this GPU.