Data Overwritten After Deletion or Formatting
Once new data is written to sectors or flash pages that held the old content, recovery changes from finding lost metadata to determining which original extents physically survived.
Before attempting repair, determine whether the storage source is identified consistently, reports the expected capacity and can be read without severe errors, stalls or disconnects. If not, treat acquisition as the first problem.
What “overwritten” actually means
Deletion and quick formatting usually change metadata first; overwrite is the later event where new writes reuse addresses that belonged to old files. On magnetic disks, sectors containing new data no longer contain the previous user data in a form normal data recovery can read. On SSDs, TRIM and the flash translation layer add another mechanism: old logical addresses may stop returning previous contents even before they are reused by new files.
Overwrite is usually partial, not all-or-nothing
A few gigabytes written after a deletion do not necessarily destroy every deleted file. Damage depends on which extents were reused. Small files, fragmented files and metadata can be affected differently. An OS reinstall is particularly aggressive because it creates many files, logs, updates, caches and temporary writes across the target volume.
How to assess the situation
Stop writes and preserve the current state. Record what happened after the loss: how much data was copied, whether an OS was installed, whether applications continued running, and whether the device is an HDD or SSD. Recovery from an image can then compare surviving metadata with actual content and identify files whose extents still contain plausible data.
What recovery software can and cannot do
Software can find old file records, locate surviving extents and carve recognizable content. It cannot reverse a genuine sector overwrite. A recovered filename therefore does not prove the associated data survived. For partially overwritten structured files, format-specific repair may salvage intact internal objects, but that is reconstruction from surviving content, not recovery of the overwritten bytes.
Why preserving evidence matters
Do not install recovery software onto the affected volume or save recovered files back to it. Each new write can consume another old extent. If a previous recovery attempt already wrote to the source, keep a record of what was done; it helps explain why some files validate and others do not.
Do not save recovered files, install software, create partitions, format, initialize or run write-capable repair tools on the only copy of the affected data. When practical, work from a verified image or another preserved copy.
Related reading: Accidental Deletion · Accidental Formatting · Os Reinstall Overwrite · Recovered Files Wont Open · What Overwrite Actually Destroys · Validating Recovered Data.
This page describes the general situation, not a guaranteed fix for a specific case. If the source is unstable or the data is irreplaceable, consider a professional evaluation before further attempts.