Sampler

Press the SAMPLER button to set the PADs to Sampler mode.

Each one of the 8 pads triggers a sample from the selected Sampler Bank of VirtualDJ. If a bank has less than 9 samples, both sides of the DDJ-SR2 will control the same samples. If a bank has more than 8 samples, the left side of the DDJ-SR2 will control samples 1 to 8 and the right side samples 9 to 16. The PAD will be lit if a sample slot is loaded and will blink if triggered.
Press the pads to trigger a sample. Depending on the selected trigger Pad mode, use SHIFT and the same pads to stop the sample.

Sampler mode – Pioneer DDJ-SX2

Sampler Pads page – VirtualDJ GUI

Use the PARAMETER buttons to select the Sampler Bank (previous/next).
Hold [SHIFT down and then use the PARAMETER buttons to select the Trigger Pad mode (on/off, hold, stutter or un-mute)

Read further details about Pads in the VirtualDJ 8 manual