Here's my interpretation (although that's not how I translated it):
Çıkmadım ki. Sen birden yok oldun. Sonra da müdür geldi yanıma ve kapatmak zorunda kaldım.
The other person accused him of leaving (the chat), but he's explaining that he didn't leave. The other person suddenly disappeared, and then in the meantime his boss came, so he had to close (the program).
Actually, I just wrote to the requester and asked him if it's OK with him if we edit the original according to what we think the writer meant. Do you agree with my interpretation, serba? It was the same as yours except for the beginning.