parsing and adding back this string

[Rajeev Prasad]

friends,
 
I am now trying to parse this string in this way...
 
x= could be anything including special character
 
string = xx:ABC,xx,x,x,x,"x,x,x",x,x,x,"x,x",x
 
string0=ABC
string2="x,x,x"
string3="x,x"
string1=xx:string0,tt,x,x,x,string2,x,x,x,string3,x
 
final string is string1