2005 audi won't start

So been driving it for about 2 months never had
any issues with the car, went to the store night
before last and when I came out to start to go
home it didn't want to start. All the lights come on
in the dash like normally, radio heat still come on
and Can hear a click when I try to turn the key, can
hear the fuel pump turning on, but coming from
under the hood is a high pitch humming seems to
be the alternator? Anyone else ever have issues
with this also the car is a 2005 audi a4 1.8t.