My Google AdSense checks used to be delivered quite regularly every month; till they changed the channel. These days it is being delivered via the DHL-Blue Dart route.
Blue Dart has its office on the same road that I have, and yet they say could not find my (centrally located) office; as a result of which they chose to send back the cheque as Undelivered – Address Unknown/Not found.
But then this apparently is the problem quite a few in India appear to be facing; as at-least 2 other MVP colleagues Nirmal (whose residence is just behind the Blue Dart office) and Geetesh will vouch for.
Blue Dart staff just does not take the efforts to search for the address and instead prefers to return the cheques! Man, was I waiting for this cheque!! 
Sent my office staff to give them a piece of our mind. They did apologize and promised to visit my office so that future cheques would not be returned!
Anyway, if ever you wish to get Google to re-issue or re-send you the AdSense cheque you can :
1) Write to adsense-support at google dot com
2) Visit Google to Request cheque reissue. You have to be logged in to your Google AdSense account.
Once you submit a re-issue request, within about 15 days, your earnings will be credited back into your account and you’ll see a ‘Check stopped – earnings credited back’ line appear on your Payment History page. If this line appears before the 15th of the month, your earnings will be included in that month’s payment cycle. If it appears after the 15th, your earnings will be included in next month’s payment cycle.
3) Request additional help at the AdSense Forums.
Google also states : “If we’re unable to complete your payment for any reason — for example, if your check is returned as undeliverable or your EFT payment rejected — your Payment History page may show a line reflecting that your earnings have been credited back to your account. If this line appears before the 15th of any month, your earnings will be included in that month’s payment cycle. If it appears after the 15th, they’ll be included in the following month’s payment cycle.”
Hope this helps someone; and hope the Blue Dart India guys sharpen up! 
PS: Was able to get my cheque re-issued promptly the next month. Thanks Google!
However, since the Blue Dart staff still cannot assure me of door delivery, and I have to send my office staff to collect it personally every month!
Should you need to track your Google AdSense check, these instructions may be of help to you!
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