Lost all my contacts on my iPhone. Can I recover in iCloud?

The iPhone 4 of my daughter no longer showed all his contacts, as if they had been erased She adjusted to synchronize with iCloud, but not on its MacBooko Pro. His iCloud account was checked online and there are no contacts either. His schedule does not appear in the Web-based application iCloud. 

We tried to turn off and on the contacts but it changes nothing. It has also restarted the phone several times, to no avail. What worries me is that the contacts do not appear when it connects to its iCloud account. Where have they gone? It happened overnight while the iPhone was plugged in to recharge. 

Fortunately it uses Gmail and most of his contacts are in, and it can retrieve the phone numbers in her text messages, but suddenly I no longer iCloud confidence to make safe backups. I'll tell him to make a backup of contact info in iTunes, after it is restored all but iCloud was meant to facilitate the backup, but apparently easy it does not mean reliable. 

I read that maybe that 'calling it Apple could restore its iCloud, but we have not tried that. Other suggestions?

Recover lost contacts on iPhone 4 without backup with iPhone iPad iPod Recovery: h

1. Select the device to scan 
2. Enter DFU mode and then scan the iPhone 4 - Click on "Start".

Press "Home" and "Power" simultaneously for 10 seconds (countdown in the display) 

After 10 seconds, release the button "Power "BUT let press" Home "for 10 seconds again 

3. Watch and recover deleted data, including contacts.