playing DVDs/files audio okay,but no video

I noticed this problem last night.When ever I play a DVD or AVI,I get sound but no picture(just black screen).
I have tried Media Player Classic,AVS and VLC Media Player.
Also tried Windows Media Player and tells me something about adjusting display settings.
I tried that and that did not correct the problem.
I have downloaded a few codecs and that did not correct the problem.
Since I have VLC Media Player,do I need to even bother with codecs?
I uninstalled and reinstalled Media Player Classic 3 different times,as well as going to options in Media Player Classic and selecting VMR9 both rendered and optionless.
I thought that the fact that I installed Avast might have something to do with it,so I uninstalled it and than again tried to play a DVD,but still no picture.
I am out of ideas as to what the problem is,other than it has something to do with my graphics/video card perhaps?If so..how do I even tell what kind of card I have?
I have been using Media Player Classic for over 2 1/2 years and never had this problem until last night.

 

It could well be the display drivers.
Look in the device manager (type devmgmt.msc from the RUN box)
Expand "Display Adapter"
right click the adapter and select "update driver".

 

I right clicked on it (Mobile Intel(R) 945GM Express Chipset Family)and selected "update driver"
It now gives me 2 options;
Search automatically for updated software
Browse my computer for driver software

I am not sure which one to choose..?

 

Pick search. It will look on Windows update for a driver.
The other option is only if you manually downloaded a driver previously
and stored it on your HDD somewhere.

 

How long does it take Windows to search online?After 5 minutes of waiting I clicked on cancel.

 

I'm surprised, It usually works. You could try Internet Explorer/tools/Windows Update
and see if that find any hardware updates.

The next thing is, if no luck above, visit the website of your PC maker,
search the model and look for updates.

 

I tried it again..This time it tried to install update(s),but Windows encountered a problem(I don't think it mentioned what the problem was).Windows suggested that I visit the website of the maker(I am guessing they mean the maker of the display adapter).

 

I don't know if this would help...?;

http://www.intel.com/support/chipsets/sb/CS-022034.htm

I am fearing that the problem might do with some kind of virus/malware/trojan that infected my system a few days a go.I installed Avast on Friday evening(the 19th)and ran a boot scan.It found several infections and so I placed them in the chest(virus vault..what ever you wanna' call it).A couple hours later is when I noticed that I was getting no picture when playing DVDs or AVIs.

 

You'd best sort out your malware/windows problems first if I were you.

You should try something like malwarebytes anti-malware.
http://www.malwarebytes.org/ and let it fix what it finds

After it's clean run the Windows command SFC /scannow
This command will check all Windows protected files to make sure their
integrity is good.

 

I tried Malwarebytes.How do I know what to fix and what to delete?

 

Take the recommended action. For more detailed advice on MWB actions,
post in their forums.

 

By "recommended action",do you mean;
Windows command SFC /scannow ?

 

NO I'm talking about the results from the MWB scan, what it found
and what you did. After you get a clean scan you can issue the Windows command.

 

I did not do anything but leave them in quarantine.I am not sure whether to restore or delete.
My Uncle is supposed to help me with it some time this week or next,so hopefully we can get it figured out.

 

It's safe to leave them in quarantine. As long as you get a clean scan now,
it's OK to issue SFC /scannow from the CMD box.

 

I will run another scan later....and thanks for your help.I appreciate it.

 

Now when I try to do the SFC/scannow,it says "You must be an administrator running a console session in order to use the sfc utitlity".

 

See this Microsoft article for info concerning this problem.
http://support.microsoft.com/kb/929833

 

Okay,I did the scan.It found corrupt files(how many,I don't know)but was unable to fix some of them.
It also said in the CMD box,this;Details are included in the CBS.Log
Windir\Logs\CBS\CBS.log.

 

Since you've got some specific Windows issues, my advice would be to follow up with
one of the Windows specialist groups . Here's a good place to start:
http://answers.microsoft.com/en-us/default.aspx