You can type German special character on your keyboard by holding down Alt key and followed by ASCII number at numeric keypad.
ä = 0228 / 132, Ä = 142 / 0196
ë = 0235 / 137, Ë = 0203,
ö = 0246 / 148, Ö = 0214 / 153
ü = 0252, Ü = 0220,
ß = 225
