Past year data to keep history

when i delete one asset from erpnext system in year 2018, but this deleted asset is register in 2017. Now i want 2017 asset register details. but which i deleted in year 2018 is not there. Actually it should be there in 2017 data history.

is any idea to keep history data in erpnext system not by keeping data backup in external drive.

I believe this gives an audit trail record that tracks who what when about document changes, but may or may not help in your case of deleted documents Document Versioning / Audit Trail coming in 7.3 [WIP]

Maybe evaluate this and report here what you find out?