plugin was working fine for last couple months, mod installed a kit plugin, he then pulled the plugin off and when he did it removed both kits plugins, i reinstalled kits by killyou, i get this error.

o.reload Kits
Failed to initialize plugin 'Kits v4.4.0' (NullReferenceException: Object reference not set to an instance of an object)
at Oxide.Game.Rust.Libraries.Command.AddChatCommand (System.String command, Oxide.Core.Plugins.Plugin plugin, System.Action`3[T1,T2,T3] callback) [0x00000] in <7b2ea410e7224babb1bbbe468cc8db51>:0
at Oxide.Plugins.Kits.Loaded () [0x0004f] in <3a4ef944afa24001b83a7fd70790bc6d>:0
at Oxide.Plugins.Kits.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0009c] in <3a4ef944afa24001b83a7fd70790bc6d>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <23ba99f131254889867c71f0bd137b1d>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <157a94ee66ab4a7991faecd1eb84be3b>:0
at Oxide.Plugins.CSharpPlugin.HandleAddedToManager (Oxide.Core.Plugins.PluginManager manager) [0x0006e] in <23ba99f131254889867c71f0bd137b1d>:0
Unloaded plugin Kits v4.4.0 by k1lly0u
No previous version to rollback plugin: Kits

does anyone know this?

If you installed the different kit plugin, it comes with the same name. Remove the config and data before adding the same plugin name from a different author.