Guide · Windows
From a screen with no signal to repairing the boot files: the checks in the order that is least likely to make things worse.
The most important rule comes first, because it is the one most often ignored: as long as it is unclear whether the data is backed up, nothing gets repaired. Every startup repair, every reset and above all a reinstallation can make the damage permanent.
If the last verified backup is more than a day old, remove the drive or boot the computer from a removable medium and copy the data off first. That takes half an hour. A failed repair without a backup costs days.
This applies in particular to devices that make unusual noises or where access has become noticeably slow. In both cases, every further attempt to start the machine is a risk.
Initial assessment
Four typical symptoms, four completely different causes. Identifying which one you have saves half the troubleshooting.
The computer does not get as far as Windows. The cause lies with the power, power supply unit, memory or graphics output. Windows is not involved at all.
Windows starts to load and then aborts. Usually corrupted boot files, a faulty driver or a failed update.
The code is the most important piece of information. Write it down or take a photo – it tells a driver problem apart from a memory fault or a damaged drive.
Messages such as “No bootable device” or “Operating system not found” mean the computer cannot find the system drive.
Approach
From harmless to invasive. Try to start the computer after each step – never several measures at once, or nobody will know afterwards what actually helped.
USB sticks, external hard drives, card readers, docking stations. A connected stick in the boot order is one of the most common and most harmless causes.
Shutting down is not enough, because Fast Startup preserves the system state. Unplug the power supply; on laptops, also remove the battery or hold the power button down for twenty seconds.
After two aborted start attempts, the recovery environment appears by itself. If Windows starts in Safe Mode from there, the problem is a driver or a program, not the system itself.
A new update, a new driver, new hardware? In the recovery environment you can uninstall a quality update or roll back to a restore point. This is the step with the highest success rate.
It fixes corrupted boot files and a damaged boot record. If it runs twice without success, a third attempt will not help either – move on to the next step.
The Command Prompt in the recovery environment lets you check the system files and the file system. Important: the drive letter there is often different from the one you see in normal operation.
This is the point from which data can be lost. Before you go ahead, check once more that the backup really is complete and readable.
Five signs that further tinkering with the software is a waste of time – and increases the risk.
Frequently asked questions
The “Keep my files” option often works, but not always – and it only keeps files in the user folders. Programs, settings, licences and anything stored elsewhere are gone. Back up first, however tempting the option sounds.
There are two ways: boot the computer from a removable medium with a live system and copy the data off, or remove the drive and read it on another computer. For encrypted drives you need the recovery key – which should be stored somewhere other than on the device itself.
Rarely. Weigh the labour time against the cost of a new device. What is always worth it is recovering the data – the data is what has value, not the hardware.
At the latest when the data is not backed up and the next step would put it at risk. And always straight away if the drive is making noises. For clients on a managed services contract, we take over via remote support as long as the computer still starts – otherwise on site.
Dipl.-Ing. Mohamed Khater
Dipl.-Ing. Mohamed Khater founded INFONET Computer GmbH in Cologne in 1992. This sequence grew out of several thousand support cases – and out of the cases in which someone repaired first and thought about the backup afterwards.
When it's urgent
A call costs nothing and can make the difference between an hour's work and losing all your data. +49 221 984300-0.
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