Windows installation in Mac issue

I have a MacBook Pro (2012 Mid) Catalina 10.15.7. I had windows bootcamp installed in my MacBook and was working fine. I increased the storage space of the bootcamp as it was almost full. After that System was not able to boot into Windows. Tried to install the windows bootcamp again with bootcamp assistant. Went thru the process step by step and after the partition step is completed the system reboots & nothing happens. It never went through the windows installation process. Waited for 30 mins still nothing happened, just dark grey screen (system was on). I had to forcefully power off the system & start MacOS and I find the bootcamp icon in the desktop & in my finder, but not showing in the startup disc.

Need help in resolving this issue.