My Space button not working can i program another button to do it.

You can use Karabiner to remap any key to just about any other key.

A quick look doesn't show a default option for what you want (Fn -> Space), but it's possible to customize the keyboard in any way once you get under the hood.

What is the age of your system? My 2011 MBP has a battery type that can swell when older and cause malfuction of trackpad and keyboard, eventually swelling. When swelled, can crack the shell and leak chemicals.

If you system is 2011 or earlier (maybe 2012 as well), it is a concern. If I am wrong about the age of your system, disregard this posting.