Ok, so just one last thing to try, and this really is a shot in the dark lol. In your My Documents folder there should be a folder named "my games". In that folder should be a folder called "Fallout 3". This is where the preferences folder is located, it is called "FalloutPrefs". First I'm going to need you to save this file as a backup. Double click it and it should open into Notepad, go to File and select Save As. Doesn't matter what you name it, "FalloutPrefsBackup" or something, and remove the backup from that folder and put it somewhere else for the time being so it doesn't confuse the program. Now go back to the original config file and double click so it opens in the Notepad. Select everything and delete. Then copy and paste all of this in there:
[Display]
iMaxDecalsPerFrame=10
iTexMipMapSkip=0
iWaterMultisamples=4
bTransparencyMultisampling=1
fSpecularLODStartFade=2000
fShadowLODStartFade=1000
fLightLODStartFade=3500
bDrawShadows=1
iActorShadowCountInt=6
iActorShadowCountExt=6
iShadowFilter=2
iShadowMapResolution=1024
iAdapter=0
iSize W=1366
iSize H=768
iMultiSample=4
iMaxAnisotropy=15
iPresentInterval=1
bFull Screen=1
sD3DDevice="NVIDIA GeForce GT 755M"
iScreenShotIndex=0
fGamma=1.0000
[Grass]
b30GrassVS=0
fGrassStartFadeDistance=7000
[Imagespace]
iRadialBlurLevel=2
bDoDepthOfField=1
[Water]
bUseWaterRefractions=1
bUseWaterReflections=1
bForceHighDetailReflections=1
bAutoWaterSilhouetteReflections=0
bUseWaterDepth=1
bUseWaterDisplacements=1
iWaterReflectWidth=1024
iWaterReflectHeight=1024
bUseWaterReflectionBlur=1
iWaterBlurAmount=4
[TerrainManager]
fTreeLoadDistance=40000
fBlockLoadDistanceLow=50000
fSplitDistanceMult=1.5
[LOD]
fLODFadeOutMultActors=15
fLODFadeOutMultItems=15
fLODFadeOutMultObjects=15
[BlurShaderHDR]
bDoHighDynamicRange=1
[BlurShader]
bUseBlurShader=0
[Launcher]
bShowAllResolutions=1
uLastAspectRatio=3
[Controls]
Forward=0011FF13
Back=001FFF14
Slide Left=001EFF17
Slide Right=0020FF16
Use=00FF0011
Activate=0012FF0A
Block=00380110
Ready Item=0013FF0C
Crouch/Sneak=001DFF08
Run=002AFFFF
Always Run=003AFFFF
Auto Move=0010FFFF
Jump=0039FF0D
Toggle POV=0021020F
Menu Mode=000FFF0B
Rest=0014FF07
Vats=002FFF0E
Hotkey1=0002FFFF
Hotkey2=0003FFFF
Hotkey3=0004FFFF
Hotkey4=0005FFFF
Hotkey5=0006FFFF
Hotkey6=0007FFFF
Hotkey7=0008FFFF
Hotkey8=0009FFFF
QuickSave=003FFFFF
QuickLoad=0043FFFF
Grab=002CFF09
fXenonVertLookSpeed=1200.0000
fXenonHorizLookSpeed=1500.0000
bGamePadRumble=1
bInvertYValues=0
fMouseSensitivity=0.0020
[Audio]
fDefaultRadioVolume=0.5000
fDefaultMusicVolume=0.3000
fDefaultEffectsVolume=1.0000
fDefaultVoiceVolume=0.7500
fDefaultFootVolume=0.5000
fDefaultMasterVolume=1.0000
[GamePlay]
bShowQuestMarkers=1
iDifficulty=2
bDisableDynamicCrosshair=0
bSaveOnInteriorExteriorSwitch=1
bSaveOnTravel=1
bSaveOnWait=1
bSaveOnRest=1
bCrossHair=1
bGeneralSubtitles=0
bDialogueSubtitles=1
[Interface]
bHelpEnabled=1
fHudOpacity=1.0000
uPipboyColor=452952319
uHUDColor=452952319
bDisable360Controller=0
Not sure if this will work or not but give it a shot. If it doesn't work or completely fails lol, just copy and paste from your backup file back into this one and it will at least be back to where it was 🙂