I had IPhone 4s, has a passcode that I know. The device is now IPhone is disabled?

Because my daughter used and tried to unlock until the phone is disabled, can I unlock without lossing all the files on it, I tried ITunes it refer me back to the IPhone to unlock by passcode. All the local Iphone service centers informed that the device needs software installation and I will lose all data on it, any help on this rergard, I don't have back up for the files.

Unfortunately no. Unless you already had it backed up to icloud then all your files are safe but if you never backed it up to iCloud or iTunes then you will loose all your files. Go on iTunes and click restore iphone. Hopefully it was backed up.