bapu, here's the default subfolder listing for the "SampleTank 2.5\Instruments" folder. Chances are that any folders besides these belong to an expansion and not to the base install. (I hope this works):
\---Instruments
+---Bass
+---Brass
| \---Phrases
+---Drums
| +---Acoustic
| \---Electronic
+---Ethnic
+---Guitar
| +---Acoustic
| \---Electric
+---Loop
| +---Percussion Loops
| | +---AfroFingerPercs
| | +---AfroMetalPercs
| | +---Anklung
| | +---Berimbao
| | +---Bin Zasara
| | +---Bongos
| | +---Cabasa
| | +---Congas
| | +---Cowbell
| | +---Darabuka
| | +---Deff
| | +---Djembe
| | +---Drum Ball
| | +---Frame Drum
| | +---Guiro
| | +---Oriental Drums
| | +---Padellina
| | +---Penta Agogo
| | +---Repinique
| | +---Shakere
| | +---Shakers
| | +---Slit Drums
| | +---Surdo
| | +---Talking Drum
| | +---Tamborim
| | +---Tblat
| | +---Timbales
| | +---Triangle
| | +---Udu Drum
| | \---VibraTone
| \---Percussion sliced
| +---AfroFingerPercs 125
| +---AfroMetalPercs 125
| +---Berimbao 123
| +---Bongos 102
| +---Cabasa 102
| +---Congas 01 126
| +---Darabuka 108
| +---Djembe 100
| +---Guiro 122
| +---midi
| | +---AfroFingerPercs 125
| | +---AfroMetalPercs 125
| | +---Berimbao 123
| | +---Bongos 102
| | +---Cabasa 102
| | +---Congas 01 126
| | +---Darabuka 108
| | +---Djembe 100
| | +---Guiro 122
| | +---Shakere 130
| | +---Shakers 122
| | +---Shakers 130
| | \---Talking Drum 86
| +---Shakere_130
| +---Shakers 122
| +---Shakers 130
| \---Talking Drum 86
+---Orchestra
+---Organ
+---Percussion
+---Piano
+---Strings
| +---Cello
| +---Double Bass
| +---Viola
| \---Violin
+---Synth
| +---Bass
| +---Drumkit
| +---Fx
| +---Lead
| +---Pad
| +---Percussion
| \---Piano
+---Vocals
+---Winds
\---~Bonus Sounds
+---Expansion Tanks
| +---Acoustic Drums
| +---AXE
| +---Bass Collection
| +---Guitar Collection
| +---Piano Collection
| +---Symphony Strings
| \---TRANCEGRID
+---Instrument and Vocal Licks
| +---Brass Licks
| +---Miscellaneous Licks
| +---Sax and Wind Licks
| +---String Inst. Licks
| \---Vocal Licks
+---Miroslav Orchestra Perf
| \---Downloadable Sounds
+---Sonik Capsules
| +---Acoustic Guitar Capsule
| +---Bass Capsule
| +---Eclectic Drums Capsule
| +---Electric Guitar Capsule
| +---Groove Capsule
| \---Studio Drums Capsule
| +---2 Dyn GM Kits
| +---2 Dyn iMap Kits
| +---MultiD GM SepDrums
| | +---MultiD GM Cymbals
| | +---MultiD GM Hats
| | +---MultiD GM Kicks
| | +---MultiD GM Rides
| | +---MultiD GM Snares
| | \---MultiD GM Toms
| \---MultiD iMap SepDrums
| +---MultiD Imap Cymbals
| +---MultiD Imap Hats
| +---MultiD Imap Kicks
| +---MultiD Imap Rides
| +---MultiD Imap Snares
| \---MultiD Imap Toms
\---SonikSynth2