writing file back to OS from BLOB

I've written two procedures one to save OS file to BLOB and one to write the file from BLOB back to OS. now when I write the file back to OS the file is getting corrupted. for eg if its a MS word doc file of its a Adobe PDF file, I can't open it after I write it back to OS.

to check what might be the actual problem, I saved a txt file to BLOB and then wore it back to OS. now when i check the txt file, it was showing hex chars.

I've tried using both

utl_file.put_raw(l_output, my_vr );
and
utl_file.put(l_output, UTL_RAW.CAST_TO_VARCHAR2(my_vr))

but the result is same.

can anybody please help?

Thanks a lot

Warm Regards
Vivek Bajaj