Now you can access to your dogechain.info wallet again till 31 December 2024. they reopened the wallet service now.

there are two kinds of keys actually in old days.

1. the raw private key. it start with Q or other number+ letters. You can use this on dogecoin core wallet. just import and do a rescan. the address will show on core wallet. then you control the dogecoin again.

2. in old days, Dogechain allow you export a backup, which is encrypted by the password. which start with: salt(+xAbcdef+abcd/efg...==)
can only be used on dogechain.info wallet before. but now there is no such option. have to do coding work on it to try to recover the Raw private key to control your doge.
wish this helps.