Pooja ,
if the phone is totally dead also not detecting by the PC there is no simple way to retrieve your data back.
1) Try to fix your phone without flashing trough JTAGs : if your phone having power related fault you can get your data back after fixing the phone
2) swapping EMMC : one of hardest repair in modern world and you may required to working condition motherboard to swap your EMMC to retrieve your data back (may be repair cost will be higher then value of phone )
3) Check on google photo or recently backup location (Google drive/ drop box/ FB photo sync) to get any of missed data