desert eagle / micro uzi (.dff/.txd)

[Gaahl]

IMG tool is the best if you know how to use it imo, just try replacing your desert_eagle.dff and .txd with the one you had before & then IMG tool-> Commands-> Rebuild Archive (might be a bit slow, don't worry)

[Mark]

I'm afraid he didn't even read the warning which usually tells to back-up your files before doing anything.

[Frodo Baggins]

You can try Spark
http://www.gtagarage.com/mods/download.php?f=2019

Here you just open gta3.img as usual and just import the files u want to replace, then hit Save.
Dont know why, but you  dont have to rebuild the archiv with that program 

[DowJones]

IMG Manager 1.5 is the best for installing mods. You can get it from here:
http://www.gtaforums.com/index.php?showtopic=354093

For example: If you downloaded a weapon pack or car mods, and are too lazy to replace files one by one then IMG Manager lets you replace all those files with a few clicks. You just put all the (txd, dff) mods you want to install into 1 folder and choose "Bulk Replace" and it will do the rest.
Took me only 2 seconds to install detailed radar mod with a bunch of car mods and weapon mods

[Fuse]

Img tool is the best.

Just google desert_eagle.dff
and desert_eagle.txd

[DowJones]

Here you go, original deagle/uzi/ak47
http://www.megaupload.com/?d=YWTLDVUX