Can there be any option readily available for rebuilding a column that is set unused by ALTER TABLE command?

Setting a column as "UNUSED" is irreversible except by rebuilding the table from backup. It is extremely similar essentially to shedding the column (with the exception that the information isn't immediately removed).

More info.

The information continues to be here however is not accessible. Your best choice would be to contact support, they might have undocumented techniques to salvage a number of your computer data. Incidentally they'll also have the ability to help you if you want assist with the process of recovery.