I was loading a large CSV into Cassandra using cassandra-loader.
The VM ran out of disk space during this process and crashed. I allocated more disk space to the VM
Having some replication would surely help you to fix this without data loss but it would come with a price.
Despite all your effort you cannot manage to recover your corrupted sstable. So you decide to remove it from your file system to start Cassandra again. If you do not have replication your data is lost. But if you have replication on the cluster, you can possibly fetch the data from other nodes. That is what nodetool repair do !
So nodetool repair does not repair corrupted sstable. Basicallynodetool repair compare tables from node to node to find missing or inconsistent data and then repair it. You can find more information on how it works here.
However nodetool repair is very expensive, it is long and uses a lot of cpu, disk and network. There is this good post about repair benefits and drawbacks.