Based on the responses, it's obvious you folks don't adapt your bikes to yourself [not recommending appropriate chainguards], rather you adapt yourself to your bikes [recommending fredly stuff like using your socks or using straps].
The OP should be looking for something like this:
That's an SKS chainboard. There's various different models out there made by various different companies. Very common on Western European commuters and townies. No more dumb crap like using your socks or strapping your right side pants.