If this tablet is as similar to the Onda V919 series as I believe it to be, then what you have to do is reinstall Android (which will obliterate the Windows partitions and whatever crap you’ve done to them) and then reinstall Windows afterwards.
However this time, maybe you should use tried and tested methods/tutorials rather than doing your own thing. Nothing good ever comes of confusing your ambition with your ability.
That day I was trying finally I went to bios enable fastboot mode then I was able to boot from my pen drive I will not buy. Otg hub and delete all the messed up partition and will install it in a freshly created partition 🙂 hope that it will work