This is pure eclipse ide feature, you probably have better luck if you 
ask in CDT or general eclipse forum.
I can guess that history has limited slots and it does not store month 
of changes. It is not really designed to replace source control system,
it probably only can remember changes for a day of activity.

Ken Schumm wrote:
> Like most things in Eclipse, the Momentics local history feature has me baffled. 
>
> We're using Momentics 4.0.1 on Windows XP SP2.
>
> In the C/C++ perspective in projects you can right click on a source file and
> select "Replace With" and "Previous from local history". In theory anyway.
>
> Sometimes this works (rarely it seems).
>
> Sometimes it pops up a dialog that says "No local history available for selected resource". That's understandable at 
times, like when a project is newly checked out from a repository, but other times a project has been worked on for 
months on the same machine and there's still no local history.
>
> And sometimes a dialog flashes and disappears so quickly that it can't be read.
>
> What's the deal?
>
>
> _______________________________________________
> General
> http://community.qnx.com/sf/go/post9071
>
>