I changed one code line in my sketch
What was it and what did you change it to?
It compiles and then gets stuck indefinitely while 'uploading'
I had a weird problem like that quite a while ago. It turned out that I had a very long comment at the end of the sketch which contained all sorts of notes to myself and code fragments that I was keeping for reference. When I removed that comment the sketch uploaded with no problem.
Another shot from the hip is, do you have a lot of string constants in your code? E.g. like this:
Serial.print("Lots and lots of these?");
If so, you might have run out of SRAM and need to change statements like that to:
Serial.print(F("Lots and lots of these?"));
which puts the string in flash ram.