Why do you keep asking me to check the bitcoin addresss?
Because if the address(es) are "empty"... then there is no point attempting to recover anything and you'd be better off just setting up a new wallet from scratch.
I posted here that when I redownloaded the old bitcoin software it overwrite the wallet.dat and changed my address as well .
There is a very important distinction between:
"Overwrote the wallet.dat and changed my address as well"
and
"updated the wallet.dat and generated a new address as well"
This is why people are wanting to know the "file
created" AND "file
modified" dates. If "file created" = 2018, then your old wallet could have been wiped.
However, if "file created" is 2011 and only "file modified" = 2018 then there is a good chance that your original wallet.dat is still "intact" and has simply been "updated"... as opposed to completely overwritten.
As for the address being changed, wallets can hold multiple address... so there is a chance that the software has simply shown you a new receiving address and still contains the previous addresses. You'd need to use a debug console command like "listaddressgroupings" to get a list of ALL the addresses currently contained in the wallet.
Can I just transfer that wallet.dat file alone into usb drive?
And then apply it into a different computer with the most recent bitcoin qt software?
The short answer, is yes. I'd also recommend that you actually make multiple copies of the wallet.dat prior to attempting to use it... and preferably work on the copies as opposed to the original file.