A person who fixes the glass portion of windows is called a glazier.
I think the most proper name would be glazier, which is someone who installs and repairs glass.
A cobbler.
What you call person who fixes light
ganders
If you mean 'What do you call someone who repairs books?' then I think the answer is a 'bookbinder'. Sources: 'Inkheart' by Cornelia Funke
A glazier.
A glazier
a chiminey sweep (cleans them) a repair man (fixes them) a contractor (builds them) A steeple jack.
dragon
Horologist
By some fixes that made Windows 7 go faster.
A Mechanic.