Then you have.
1. A virus infecting the system, or malware.
2. A corruption in the windows registry.
3. If it has happened in the few days, or installing software ect.
Simply use windows restore, as it creates a restore point if new software is installed as a check point for recovery.
Select a point before the new software, update was installed by the date or time stamp.
Think of it this way what Did I do last before it was working. That is why restore exists because part of the problem is what the user does, and forgets.
Often the last action is result of the cause through user intervention, or malware, viruses impair the system.
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Hey, for option 3. i dont have a restore point. how fix this help...