Darren:
1.You should apply for a duplicate I-94 try to get it from Local BCIS office or apply to your service center, you have to fill up the form and pay the fees, if you have copy of I-94 attach it, talk to attorney.
2. You should surrender your I-94 when you leave for India.
3 you do not need to surrender I-94 if you take flight from Canada as it is US matter and nothing to do with US, but you may have problems later.
One is not supposed to surrender I-94 if your visit to Canada or Mexico is less than 30 days.
4. When one surrenders I-94 while leaving US the I-94 is surrendered at airlines counter and all the I-94 are collected from Airlines by BCIS or BCBP and then entered in BCIS computer data that you left US on particular date. It you proof that you left US and your stay in us was authorized and you complied with your status, if any miss match is found later in can haunt you in the future for any US visa or your GC process.
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deepred:
one of my friends went home to India from Vancouver without surrendering the I-94 and he came back after a year (just recently) and no questions were asked since he got a new I-94 while entering.
--- It means his departure from USA was not recorded when he left from USA, he may be having Valid visa and valid I-94 till the time he re-entered US. Did he entred US directly from India or from Canada?
What is strange is: besides the airline records, how would Canadian authorities ever know when he left Canada??
--- Canada can know from his departure records to India, he has also stamp on his passport when he entered India
Or for that matter, even the BCIS?? 'Coz he drove from Seattle to Vancouver and didn't have to submit his I-94 at the border.
---- BCIS may not know as he left from Canada for India, but in future they will know from his passport stamp and from new I-94 when he entered US, it may cause problems later he should keep his record/evidence of departure from US.