Number 1
The first way I would proceed with the situation is to assess it and try to understand why the power is out firstly. If the power in the whole laboratory isn't off, then it means that it's something to due with that specific area. After investigating the power- I'd proceed to power it back on, if possible.
Number 2
We need to first make sure the reagents are still acceptable for use. Their chemical safety must be checked and maintained, to ensure the best for their quality and if they are still acceptable. The proper way to deal with this situation is to view the data on the chemicals- the reagents. You can do this by checking the MSDSs (Material Safety Data Sheets). This will give you the information you may require about the chemical details and even more.
Number 3
This situation could have been avoided by making sure the power doesn't go back out. We can prevent the power from going out- if we know the reason it went out the first time. If required- a new refrigerator for storage could be used, or another outlet should be used. This could have been prevented.