GS500RIDER

Hello Guys,
I am new here just brought a "91 GS500.
Its rides perfect, very smooth. I am a beginning motor rider so this is my first bike.

My name is Joran and i live in Holland (thats why i am speaking in English, Sorry my english is not the best)

My Problem:
I had to change the olifilter but when a closed that cap for the olifilter one of my screws broke. (the left one, the one not on the side of the brake)
Yes i know that a commen problem but is there any way to fix this?

PLEASE HELP i need my bike to get to my work!

THANKS!!