You said you were originally near minefield, some of the forums say that the crash is then located
north of MDPL-13 Power Station and northwest of the Greener Pastures Disposal Site. .
Even if you were to find the location again there is only one alien blaster per game unless you happened to drop it at the same location where you found it.
In any case, if you can remember the general location, you can scout around until you pick-up the distress signal from Recon Craft Theta on your pep-boy. That will tell you you're close along with the increase geiger counter activity.
Other than finding the one you lost the only other way would be to use the console and "give" your character the blaster by entering the correct code.
The console is opened by hitting the "~" key. To give your character the alien blaster you would need to type in the following:
player.add item 00004322 1 100
and hit enter. If that doesn't work try dropping the leading zeros on the item code.