~snip~
AFAIK, after you reinstall metamask you will see "welcome page" that contains:
1. Import Wallet (using 12 "magic words"/seed phrase only)
2. Create New Wallet and seed phrase.
So, if you want to import/recover your old metamask after format your harddrive, you should use the right 12 word seed phrase.
There's no other way.
first i tried to use seed phrase but it says its wrong. (1st and last words are same, is it possible?)
I think 12-word seed phrase is unique words, can't be same at each word.
Try to remove the same words at first or last.
then i tried private key from my notes, i can login but its not my wallet.how can it be possible?
That's mean, the private key that you use is not belonged of your old wallet.
But I'm curious, how can you get into metamask? Even though metamask doesn't need a private key to recover the wallet address.
Metamask only uses 12 words seed phrase.