Hey Zeyad,
I am assuming your string vector was s. To get an index vector you would have run.
[g,gN,gL] = grp2idx(s);
You can reproduce input argument s using the output gL:
gL(g(:,:))
You can also use gN(g) to reproduce the input argument s as a cell array of character vectors.
gN(g(:,:))
Checkout the examples in the documentation to know more about the conversions
