I'm following this tutorial and while doing the I2Cscanner it shows this.
It can't detect my I2C. My SDA->A4, SCL->A5, VCC->5V, GND->GND. Already downloaded the library and changed lcd(0x38) to lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE). But when I run i2cScanner, it shows the image above. I don't know what's wrong with my lcd. 
I don't know what's wrong with my lcd.
It is not working.
Either it is broken or something is not wired up like you think it is.
How about a photo ( no more than 1000 pixels ) of the wiring and a schematic.
Do you have pull up resistors on the data and clock?
Here is the pic:
Grumpy_Mike:
Do you have pull up resistors on the data and clock?
I can't see the colours on those resistors clearly but I think they are 200 or maybe 270. They should be about 4.7k.
Pete
el_supremo:
I can't see the colours on those resistors clearly but I think they are 200 or maybe 270. They should be about 4.7k.Pete
I don't have 4.7k. But I saw some videos they just connect the pins directly and it works. I'm really new at this. My first lcd is defective but it doesn't have i2c. My friend bought me a new one but it has this i2c.. So I don't have much of a choice but to configure this. I don't know what to do. 
Sorry for my noobness.
Does it work without the pullup resistors?
If not, what resistors do you have? You might be able to put some in series and/or parallel to get a resistance near 4.7k.
Pete
my scanner also checks at different bus speeds - MultiSpeed I2C Scanner - 50,100,200,400 KHz. - Libraries - Arduino Forum -
give it a try
Did no-one look at the photos? 
He is not using a UNO; it is a "Gizduino X - 1281" board. I presume it is equivalent to a Mega2560 on which SDA and SCL are pins 20 and 21 instead of A4 and A5.
Not only is it complete nonsense to start talking about pull-ups (which are probably already present on the backpack - haven't checked that) - but he has misunderstood what a "pull-up" is and put resistors in series with the control lines.
Get rid of the nonsense resistors, connect to pins 20 and 21 and go from there! 
Paul__B:
Did no-one look at the photos?He is not using a UNO; it is a "Gizduino X - 1281" board. I presume it is equivalent to a Mega2560 on which SDA and SCL are pins 20 and 21 instead of A4 and A5.
Not only is it complete nonsense to start talking about pull-ups (which are probably already present on the backpack - haven't checked that) - but he has misunderstood what a "pull-up" is and put resistors in series with the control lines.
Get rid of the nonsense resistors, connect to pins 20 and 21 and go from there!
It worked sir! Thank you so much!! Thank you! Thank you! Thank you!!
Paul__B:
Did no-one look at the photos?
sharp eye,
just assumed it was a UNO clone 
