Replace all the special characters of other language scripts to English alphabets

[Badagala_Jagadeesh]

I have 10 columns … Every column has strings like “Dági Általános Iskolásokért Alapítvány”
and I need to replace to “Dagi Altalanos Iskolasokert Alapítvany”
and Äü to AU…
can you please let me know the best way to do this ?