WHAT ARE THE DIFFERENT CAUSES OF THE PEAK SPLITTING ?
WHAT I KNOW IS VOID VOLUME WHAT ELSE CAN SPLIT THE PEAK?

there are several other possible factors.

A partially clogged guard or column inlet can split a sample peak. changing the guard would solve this.

a dried out column may also develop channeling where analyte travelling on one side of the column has a shorter route than the other.

I've been told that pH can also cause peak splitting. The ionized form of your analyte will have a different retention than your neutral species, which will cause peak broadening and even split into two peaks (though I've not seen this or fully believe it due to the rapid proton exchange, a molecule would not stay ionized or neutral long enough to resolve) anyway, altering pH to get the neutral species generally improves chromatography.

some other reasons may not be chromatography related.

isomers and multiple chiral centers of your analyte can cause different retention times and be seen as multiple peaks.

in Electrospray MS detector, concentration can alter ratio of dimer-cations to single-cations. Thus at the crest of elution, more species is 2M+H(or Na etc) instead of M+H and a "split" is seen in the M+H signal mass/charge. Diluting analyte should take care of this.

those are some reasons I can think of.

If you use ion-pairing reagents, peak splitting is sometimes observed if the concentration of your ion-pairing reagent is too low for the quantity of sample injected, or if your sample is dissolved in an inappropriate solvent (wrong pH), ...
Check if your problem is related to your equipment, just the column, just the mobile phase, or maybe just one sample...

the most common peak splitting I've experienced has been caused by the sample diluent being higher in organic than the starting run conditions. So, if for solubility reasons the sample is in 80%ACN, but the starting gradient is only 10%ACN, the early eluting peaks are split due to the solvent front. This can be minimized by injecting the smallest feasible injection volume, but may still cause a problem. The best scenario is to match the sample diluent to the starting MP whenever possible.

THANKS For YOUR REPLIES ,
MY PROBLEAM IS SOLVED BY THE LAST TIP GIVEN NY ANNOYMOUS
THANKS A LOT TO CHROMFORUM FOR PROVIDING WONDERFUL PLATFORM TO DISCUSS THE CHROMATOGRAPHY,

thanks for the tip Anon.

I routinely use MeCN as the solvent for my samples yet, about 65% aq in the beginning mobile phase. I'll keep this in mind next time I see splitting peaks.