recover record , no warning message when memory space ends in the middle of a recording session

I was recording voice with my sansa clip+ 4 GB
It was a 1 hour recording
When finished I tried listening to the recording, it was only 3 minutes long
And another file appeared (the file name mysteriously was named by date to a day after) , this file could not be played , when trying to play it , it stays at 00:00 and does not play.
I tried recording again …. This time I was looking at the screen and recorded for 30 seconds, all looked fine, then I tried to hear it, but the file was only 3 seconds long.
On the third time when trying to record a message appeared memory full….
(Then I understood what happened in the first place, all thou the memory was only 3.41 GB full ?!?! )
That’s probably what happened to the first 1 hour record (the memory space ended probably after 3 minutes but it continued to look as if its still recording…)
Another mysteries thing: in my device - voice => listen to recording=> I see 6 fils
When I connect the device to my PC , on the I:\RECORD\VOICE folder I see only 3 fils.
Bottom line :

  1. Is there any whey to recover my first 1 hour record ? (critical)
  2. is there no warning message when memory space ends in the middle of a recording session ?
  3. What’s the record time capacity for the sansa clip+ 4 GB?