Screw loose after crash

[Didbach]

Hi guys, 

 

Had my first trip over the handle bars yesterday and noticed today my right break has a screw loose (missing now). I have attached pics, please can anyone let me know if this is important or what its function was? 
 

Thanks in advance  

[fanievb]

That screw keeps the mineral oil (brake fluid) where it's supposed to be.

Without it, your brakes are essentially useless, suggest you visit your bike shop, before you ride again

[Jimmy 2.0]

that screw is the bleed port for your brakes. i suggest take it to your bike shop and ask if they have one lying around, maybe ask them to bleed the brakes as you might of lost a bit of oil.