Reddit mentions of Original Sin

• Thor: God of Thunder Volume 4: The Last Days of Midgard
  
• Original Sin: Thor & Loki: The Tenth Realm
  
• Original Sin
  
• Thor Vol. 1: The Goddess of Thunder
  
• Thor Vol. 2: Who Holds the Hammer?
  
• Mighty Thor Vol. 1: Thunder in Her Veins
  
• Mighty Thor Vol. 2: Lords of Midgard (Coming this month)

This run covers him losing his arm I believe:

https://www.amazon.co.uk/Thor-Jason-Aaron-Complete-Collection/dp/1302922955/ref=mp_s_a_1_1?keywords=thor&qid=1563826455&rnid=1642204031&s=books&sr=1-1

While this is the run leading up to it:

https://www.amazon.co.uk/Thor-Jason-Aaron-Complete-Collection/dp/1302918109/ref=pd_aw_sbs_1/258-0536864-7819462?_encoding=UTF8&pd_rd_i=1302918109&pd_rd_r=f0c8e31a-ceb9-4360-baed-aee70a978761&pd_rd_w=JEf67&pd_rd_wg=YacOv&pf_rd_p=d9539b3c-75e6-4bff-a48d-94806c2c2f83&pf_rd_r=B4V0STNEBHGSCQAZZME1&psc=1&refRID=B4V0STNEBHGSCQAZZME1

Edit: I would start with the second link there, although that is purely Thor Odinson as Thor as that is the story beforehand. You may also want to read Original Sin after that before moving on to the first link I gave you, because that shows where Thor loses his hammer. Here’s Original Sin:

https://www.amazon.co.uk/Original-Sin-Jason-Aaron/dp/0785154914/ref=mp_s_a_1_2?keywords=original+sin&qid=1563826715&s=gateway&sr=8-2

Edit again: Also, if you want to follow Odinson more, read Unworthy Thor. The links I sent you are amazon UK, so if you’re not in the UK you probably don’t want to order straight from the links I sent you.