That message comes from a permissions system, not from a fault. What remains is to work out why your rights changed - and that is where the causes diverge.
Windows assigns every file to a specific user account, identified internally by a unique number. When that number no longer matches, access is denied even if the account name is identical. That explains most cases.
For a personal folder you legitimately own, the operation means declaring yourself the owner and passing that right down to everything inside. It is done from the folder's properties, Security tab, Advanced button, by changing the owner and ticking the option to apply it to subfolders.
On a large folder the operation can take many minutes. Two precautions : do it from an administrator account, and confine it to the folder concerned - never apply this treatment to the root of the system drive, it destabilises Windows.
A read-only file is not the same as access denied. The box is unticked in the file's properties. If it keeps coming back, the file probably came from an attachment or a download, and Windows marks it as coming from an external source - an Unblock button then appears at the bottom of the properties window.
If the files were encrypted with the EFS file system or protected by BitLocker, no amount of permission work will make them readable : the certificate or the recovery key is required. And if the files have appeared renamed with an unfamiliar extension alongside a ransom message, this is not a permissions problem but ransomware - see removing a virus.
Do not change the permissions of system folders hoping to fix a general problem : it is a classic source of instability, and it opens up access that should stay closed. If the refusal concerns a system location, the cause lies elsewhere.
Taking ownership of documents recovered from an old machine is among the jobs we do routinely, including remotely. We check along the way that nothing was lost in the transfer. See also data recovery.
Being an administrator entitles you to take ownership of a folder, but does not automatically give access to files belonging to another account. Ownership has to be taken explicitly.
No, it only changes access rights, not the contents. The only real risk is applying it too widely, to system folders.
No. That is the sign of ransomware encryption, and no amount of rights work will change it. Switch the machine off and have it examined.
Would you rather we took care of it ? See our computer repair at home service, in Lyon and across the Rhone.
We restore the rights and check that nothing has been lost.
Automatic assistant: it can make mistakes. Never share a password or a card number.
