Microsoft VBScript compilation error: Expected 'End' What is wrong with the code?

sInput = InputBox("Enter your name")
a=MsgBox("You entered: " & sInput , 4+32 , "Is that what you want entered?")

if a = vbyes then

b=msgbox("thanks" , 0+16 , "thanks")

If a = vbNo Then

c=msgbox("retry" , 5+64 , "retry")

If c = vbRetry Then

sInput = InputBox("Enter your name")
a=MsgBox("You entered: " & sInput , 4+32 , "Is that what you want entered?")

if a = vbyes then

b=msgbox("thanks" , 0+16 , "thanks")

If a = vbNo then

c=msgbox("retry" , 5+64 , "retry")

Else

end if