[SOLVED]Toggling LED on Arduino Uno with a switch.(IDE used atmel studio)

Hey, so i am using an Original Arduino Uno Rev. 3 Board to toggle the inbuilt LED using a switch. If i connect the switch on any PORTB pin, and set that particular pin to high. Then high voltage level on that particular pin is 2.0 V as measured by my multimeter. Due to this the inbuilt LED always stays on.

/n can be any 0 to 4 pin of PORTB/
#define F_CPU 16000000UL
#include <avr/io.h>
#include <util/delay.h>
#define LED_ON PORTB = (1<<PB5)
#define LED_OFF PORTB = (0<<PB5)
#define LED_Blink PINB = (1<<PB5)

int main(void)
{
DDRB = (1<<PB5);
DDRB = (1<<PBn);

while (1)
{
PORTB = (1<<PBn);
if(!(PINB & (1<<PBn)))/Reading pin state,If pin is low turn LED on/
{
LED_ON;
}
else
{
LED_OFF;
}
}
}

Now if i take the same code written above and just use PORTD to toggle the LED with switch. Everything works fine, which means If i connect the switch on any PORTD pin, and set that particular pin to high. Then high voltage level on that particular pin is 4.95 V as measured by my multimeter. Due to this the inbuilt LED can be toggled.

/n can be any 0 to 7 pin of PORTD/
#define F_CPU 16000000UL
#include <avr/io.h>
#include <util/delay.h>
#define LED_ON PORTB = (1<<PB5)
#define LED_OFF PORTB = (0<<PB5)
#define LED_Blink PINB = (1<<PB5)
int main(void)
{
DDRB = (1<<PB5);
DDRD = (1<<PDn);

while (1)
{
PORTD = (1<<PDn);
if(!(PIND & (1<<PDn)))/Reading pin state,If pin is low turn LED on/
{
LED_ON;
}
else
{
LED_OFF;
}
}
}

The board is fine as well, I made all PORTB & PORTD pins high and check the voltage level on those pins and it came out to be 4.95V only. Below is the code i used to do it.

#define F_CPU 16000000UL
#include <avr/io.h>
#include <util/delay.h>

int main(void)
{
DDRB = 0b00111111;
DDRD = 0b11111111;

while (1)
{
PORTB = 0b00111111;
PORTD = 0b11111111;
}
}

If anyone can provide answer to why the inbuilt LED cannot be toggled using switch on PORTB, will be helpful! Also why am i getting the PORTB pins HIGH voltage level to 2.0V instead f 4.95V when i am trying to toggle an LED with a switch will be a big help as well.

Please read the forum guide in the sticky post, then modify your post above and correct it.