How Do I Unlock My Fly Slt100 Phone For Free?

I have a fly phone as known model by (Fly Mobile) SLT 100 VIRGIN but I had restore setting all the Mobile Phone. Now it is'nt pick up the sim connection. It required Master code. So Please send me it Master Code.
I shall be highly thankful to you for this act of kindness.

Normally unlock codes (also called subsidy unlocks) are provided by the wireless carrier, which means in your case a call to Virgin Mobile.  If they cannot provide it, then for it to be released for free, that must come from the manufacturer.

Also, if the device you are referring to is a Firefly, then no, that is not  unlockable.

I don't think that you can do that