Hey sridevi, the best route to reach coorg is by bus, there are a lot of busses from gadag to mysore, and rightly from mysore to coorg, apart from that if you are okay a little jiggling, then i would ask you to take a train from gadag to hubli and from hubli to arasikere and from there to mysore. So well talking about coorg, its not yet rejuvenated from the damage occured 2 years in a row now, nevertheless, it still has a lot of things to offer, like raja seat, abbey falls, and mandalpatti peak,if you rent a var then you can even visit talacauvery and bagamandala. Hope this helps, good luck and cheer's !!