1. Check that you have connected the HC05 Module with UNO as per following diagram. The voltage divider circuit is needed as the RX-pin of HC05 is not 5V tolerant.
2. Is the Red-LED of the BT Module continuously blinking?
3. Have you installed a Bluetooth Terminal (BTT) in your android based smart phone?
4. Check that the smart phone has detected your BT Module. If SN is asked, enter 0000 or 1234; they usually work.
5. Connect your BTT with the BT module. Check that the RED-LED is now blinking once a while.
6. Upload the following sketch in the flash of your UNO.
SoftwareSerial BTserial(2, 3); // RX | TX
// Connect the HC-05 TX to Arduino pin 2(as RX).
// Connect the HC-05 RX to Arduino pin 3 (as TX) through a voltage divider.
byte x = BTserial.read();
byte y = Serial.read();
7. Check the functionality of the communication link:
BTT <----> BT <----> UNO <----> Serial Monitor