Formatting.. installing... they are very different things. It could be that Setup thinks it has written files but there are errors which it has not noticed upon resuming installation.
Okay, try a full check of your disk surface - you can get Setup to do that: start Setup afresh, if there are no other partitions on it then delete the old partition and create a new one, then or else do a Full Format of your selected partition, go on with the installation.
[A quick format deletes the old Master File Table, a full format does that plus chkdsk of that partition].