How can you tell if a woman has feelings for another woman?

Give her some time. Maybe she stopped messaging because she might be too shy and maybe she's trying to figure things out. I can't say whether she does or doesn't feel something, but if you want to know, it's better to simply ask her. What do you have to lose?

My friend was in a type of situation kind of similar i guess. She really liked one of her friends and really wanted to tell her, she talked to her about it and after they talked she said her friend was being distant and seemed awkward. She didn't text her anymore and my friend was really hurt and she felt like a disappointment, I felt so bad for her. Their still going through the issue, i guess the question is do you like her? If shes shy she's probably never been in the situation where she likes another girl and doesn't know how to approach the situation.

"She has stopped responding to all text messages" seems kinda clear to me: no interactions outside of work, and at work she maintains a level of polite interaction because you are in a professional context?

Well, the question was answered today. She said I've been blocked on her phone. Ouch. And wow. Her lose, not mine.