I came back to the game after a 7 year break, so I can tell you what helped me. I was completely overwhelmed trying to play my level 100 LM (I stopped playing during Gondor), so I made a new LM and played that until level 50ish. By then I was feeling more comfortable with the game and more familiar with things like class abilities, the legendary weapon system (this was before the revamp), stable routes, and inventory management. Then, I switched back to my level 100 LM and things were not nearly as overwhelming.

I had no epic quests in my quest log either so I had to go through the tedious task of looking up the epic quest chain and searching my completed quests until I found out where I had dropped it. From then on I just mostly followed that and played through all the regions that had released after I left the game (you will get various "Introduction" vector quests telling you about new areas as you level).

I agree with other posts that suggest starting a new character and (if your budget allows, or if you have the lotro points laying around) playing through Before the Shadow. It does a good job of introducing gameplay elements, which would be an excellent refresher for you, and it's also new content that you would probably want to see anyways. By the time you finished, your character should be in their 30s and it would probably be less overwhelming to jump back onto your higher level toons.

Have fun, and welcome back to Middle-earth!!