MacOS uninstalled after installing bootcamp during windows partioning
This question if difficult to answer, because of the lack of information. The most likely answer is to boot to macOS Recovery over the internet and install macOS.

Other information that would have been helpful include the following.


The version of macOS that was installed.
The model/year of the Mac.
The version of Windows.
The Windows boot method (BIOS or EFI).
The current entries in partition tables (GUID and MBR).
The method use to install Widnows (DVD, flash drive, Boot Camp Assistant).