tried tracking my phone through android device manager. having trouble doing so.help!
I think that you can use Google instead of Android Device Manager in your particular case. Today it happened to me the very same thing that happened to you and as in your case Android Device Manager was of no use. But I typed find my phone in Google and it gave me map centered around the place where I had actually forgotten my phone. It seems the map cannot be zoomed in, but at least it can give you an hint about where the phone was before discharge.
Here's a screenshot of what I got from Google.

Better than nothing I suppose.