From your description, it seems you’ve made a royal mess.
I have the feeling it might take hours of our time extracting information from you to fully diagnose the problem and longer to have you perform any recovery tasks, if that’s even possible.
As a final resolve, I might suggest the following:
1. Copy your important work somewhere safe; to external USB(s), for example. Boot with a Manjaro Live environment (Manjaro ISO) if you need to.
2. Use this general guide to reinstall each OS:
The key to minimise many potential problems while installing is to make sure that only the disk you are installing to is connected during installation of each OS…
Disconnect the intended Manjaro disk while installing Windows, for example. This is important regardless of the type of disk.
As you seem to have ignored the information and requests from the Moderator @BG405 I’ll drop the following for consideration:
The following text is pre-prepared to assist new forum users.
Welcome to the Manjaro community.
As a new forum user, please take some time to familiarise yourself with Forum requirements; in particular, the many ways to use the forum to your benefit:
Required Reading:
Resources:
Update Announcements:
The Update Announcements contain update related information and a Known Issues and Solutions section that should generally be checked before posting a request for support.
System Information:
Output of the following command (formatted according to forum requirements) may be useful for those wishing to help:
inxi --admin --verbosity=8 --filter --no-host --width
Be prepared to provide more information and outputs from other commands when asked.
Regards.