I dont have my private keys, how can i find it if i have only the Pubkey and the insight_bitcoin files in JSON format ?
With only this information, you can't.
Since you have found the file in the electrum directory, you most probably have used electrum ?
Do you remember installing it ?
Also.. did you do what nc50lc suggested ?
This is the directory of electrum's wallet files (which contain all of your private keys).
how insight_bitcoin files can be on my PC ? is a proof a last missed transaction?
You can not 'miss' a transaction.
Transactions are broadcasted into the network. Once they are included in a block, they are
confirmed.
You don't need this information to access your btc. You only need the corresponding private keys.