While this will almost certainly resolve any BOOTMGR errors, it's a time-consuming process due to lớn the fact that all of your data must be backed up & then later restored.
Ọ bụ ezie na nke a ga-emecha dozie nsogbu ọ bụla BOOTMGR, ọ bụ oge na-ewe oge n'ihi eziokwu ahụ bụ na a ghaghị kwado data gị niile wee mechaa weghachite.