LINE has a built in chat backup utility for the mobile version. Unfortunately you need to enable this before you lose access to the app/phone. Enable it in your setting now so that you can restore your chat history to your device.
i had suddenly a message from LINE that i had to re-install it. as i did so, i have now a blank LINE (no chats any more).
but i have also a LINE on my PC. how can i now re-import the chats onto my android? i found a solution which is outdated: https://www.backuptrans.com/tutorial/restore-line-chat-history-to-android-from-pc.html i bought it ($ 20) just to find out that it doesn't work!
it's a shame you don't help with something LINE just did wanting a new installation!