I just updated Friends plugin and on checking the config to edit found that most of the old configs had disappeared,
Here is the old config (backed up due to server problems) from July this year,

{
  "DisableFriendlyFire": false,
  "EnableFriendChat": false,
  "EnablePrivateChat": true,
  "LimitFriendChatToMutualFriends": true,
  "MaxFriends": 30,
  "Rust": {
    "ShareAutoTurrets": true,
    "ShareCodeLocks": true
  },
  "SendAddedNotification": true,
  "SendOfflineNotification": false,
  "SendOnlineNotification": false,
  "SendRemovedNotification": false
}​

Please see the changelog on the Updates tab. The majority of those settings never existed in this plugin either, so I'm not sure which version you were using. The previous version doesn't have any of the send options, friendly fire handling, or chat handling.

This is the version i have been using downloaded from Oxide and originally developed by *i think Nogrod, I (as i said) backed up my configs in July so this is the config i had, i dont download from other sites (except for one recently removed from here) So this is the only version i have.
I also note that /help no longer shows this plugins options and when i type /friends i get "unknown command" , I dont get a syntax correction as you would if you typed "/chat group" for instance.

This would i guess be the original version before plugins were migrated over to Umod .

I'm still not sure what version you had, but the latest version was migrated here is the previous version listed under Updates. Either way, the plugin was updated to be universal and focus on being an API and manager rather than what friends can or can't do. Other plugins can (some already exist) provide the additional functionality while using this plugin as the base, similar to how Economics is.

This version

Friends

Moved

Total Downloads: 7,097 - First Release: Sep 7, 2016 - Last Update: Nov 19, 2017 ​

and as Dcode (dev) posted in 2016
The plugin aims to be API compatible with FriendsAPI

So this is actually an update/replacement of FriendsAPI and has no player functionality at all ? , cannot add/remove friends etc ?

Sounds like the dcode Friends plugin is what you were using then, which is not the same as this plugin. This plugin provides a friends list and API, like it always has, for other plugins to utilize. The command is current "friend", which is what it was in the previous update as well.

Both this plugin (originally only for Rust) and the Friends plugin by dcode were named Friends.cs.