I was wondering if there is a better phrase without sounding rude, to ask co-worker(subordinate) if I can still expect her/him to finish the assigned task after a quite long time after the last communication.
I'm thinking about writing..
"I didn't hear from you for long time. Wondering if you are still interested in working on that task?"
I'm sorry I haven't followed up with you before this. It's been a while since we last talked about [creating that presentation, whatever.] Is that still something you're working on? If so, do you have an estimate on when it might be completed? If you have any questions or if you'd like to talk about it in more depth, please give me a call.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.