what should i do when input output pins are not sufficient for connecting?

Need help, What do we have to do when using arduino uno board micro controller analog and digital input and output pins are not sufficient for connecting more sensors or required components? please reply

Use an I/O extender, or a different board.

Tell us what you have connected, there are many tricks to add something extra.
Most sensors are I2C or SPI, that should be no problem, is it ?
Buttons can be set in a matrix. For example 3x3 for 9 buttons requires 6 pins.
Analog inputs A0...A5 can be digital input or outputs as well.