Note: This was written in December 2015 and has not been updated.
In the last few months, there have been a number of articles in the popular media and rail fan groups regarding the demise of the network of narrow-gauge lines in Central India known as the Satpura Railway, now coming under the South East Central Railway.
If you were to take these articles seriously, you would imagine that these lines were being permanently closed down leaving this area without rail communication. They are, of course, being converted to broad gauge and this network has been gradually converted over the last decade. You can expect the conversion to be over within a couple of years.
Here we have an 1964 map of the then SER which shows all the NG lines long before Project Unigauge was even thought of.

Note the numerous NG branches all over the zone. However, the Raipur branches and everything east were not part of the Satpura system.
For the moment, however, there still exists one functioning narrow gauge line between Nagpur and Nagbhir which has three pairs of trains a day. This will also face the conversion axe sooner or later, but you can certainly travel there now. Thanks to local expert Alok Patel for this tipoff.
Here you can see the overall list of trains (from an official website, but errors are not impossible):
Nagpur-Nagbhir:

Nagbhir-Nagpur:

Here are the timetables for the first trains in either direction:
Nagpur-Nagbhir:

Nagbhir-Nagpur:

Note that the station of Moti Bagh was known for its narrow-gauge loco shed and other workshops (besides a small railway museum) but was not used for regular passenger services. I do not think it appeared in passenger timetables until now.
For instance, it is not there in the printed timetable of 2014. That shows the first train leaving from Nagpur at 05.55. The second train given above is shown at Itwari at 10.10/10.15 and then at Nagpur at 10.45.
So the laments for the demise of the narrow gauge Satpura Railway were a little premature. Ride this 110-km route south of Nagpur while you can. There are also a few BG trains running through Nagbhir. These include an express between Chennai and Bilaspur (once weekly in each direction) and between Yesvantpur and Korba (twice weekly).
This map showing part of Nagpur may be helpful:
https://www.google.co.in/maps/@21.1552413,79.1014885,15z
Incorporating a few comments received from my old friend Alok Patel:
“Conversion has been sanctioned for the NGP-NABN line but no serious allocations done yet. I suspect they will want to complete the main Satpura lines first since the Nagpur-Chhindwara-Jabalpur-Gondia network had surprisingly high traffic. Also note that the station code for Nagbhir Narrow Gauge has been changed to NABN to signify NG. The BG station must now be using the code NAB”
“I haven’t been to MIB for a long time now but the trains don’t start from MIB per se. They start from the MIB yard, go to NGP, reverse at NGP, go down the same route till the triangle at MIB where they stop to pick up passengers, bypass the MIB yard at the triangle and continue towards Itwari. I suspect the one kilometre or so long NGP-MIB stretch won’t stay operational for much more time, now that the key Chhindwara side traffic has ceased to exist.”