Hi there,
It is very rare to have such a case if you are applying to typical consulting companies - If the partner you are interviewing is head of the restructuring practice, that does not necessarily mean you will get a case from that topic.
If you are super sure that the case is coming, then I would recommend practicing profitability and cost reduction cases (at the end of the day, a restructuring case is a profitability case with a bigger focus on the cost side and identifying which business units to keep vs. sold)
In terms of calculation, be comfortable around a P&L and the key ratios of a balance sheet + NPV calculations (with annuities, perpetuities, and if they are growing or not)
I hope this helps.
Khaled