how to rescue the qnx4 partition?

3.0 GB hard disk with qnx 4.25.

Today I use the fdisk utility of dos to delete the qnx partition and create a 2GB -size primary dos partition.
After reboot, the qnx cannot boot.

How can I rescue the qnx partition?

If you remember the partition size and did not write to the dos partition you may try recreating the partition. Otherwise I think you are pretty much out of luck. Were you expecting QNX to boot even having its partition deleted?

Even if you wrote over the partition, it might still be possible to recover some data from the QNX partition. This is a somewhat technical area. There is some documentation around. Basically, you dinit the disk, and then start searching for special file header strings. When you find a file or directory intact, you can relink it to the root. While you could in principle use such a disk, after running chkfsys on it, I would just copy any files off and start over.

Thank mario and maschoen!

There are 2 disks in my system. I meant to operate a 32m cf card, but because of my carelessness, I has operated that 3g hard disk.

I have not write to the dos partition. Now I will try to use dinit rescue it.