I'm a beginner and currently learning to play guitar. I have a polo acoustic guitar. when I try to tune it using a clip on electronic tuner it doesn't recognize the strings correctly. except for 6th and 2nd string it recognizes all strings wrong. then I tried with a tuner app using my phone but same result it also doesn't recognizes the strings correctly. I don't know what to do and what is the problem. as I'm a beginner I don't know how to tune without a tuner.Please help.
Evidently the strings are so out of tune that the tuner can't know anymore which is supposed to be which.
Lucky that it did recognise the 6th string, because from that you can easily tune all other strings by ear. Just compare the pitch that's produced when fingering the low E-string (6th string) at 5th fret with the empty A-string (5th string). It should be the same pitch, but it won't be necessary to get it exactly right: once you're close enough, the tuner will be able to track the A-string too. Just make sure you hear whether it's much too low or already to high (never tune a string much higher than it's supposed to be), and correct it.
Once you got that, you can repeat the procedure: the empty d-string should have the same pitch as the A-string on 5th fret. And the empty g-string is the pitch of the d-string at 5th fret.
You already have the b-string tuned. (Attention: this one is not the same pitch as the g-string on 5th fret, but 4th fret!) Then the high e string is again like the b-string on 5th fret.
This tuning technique isn't very good for actually fine-tuning a guitar by ear, but it should get you close enough so you can use the clip tuner.
Your clip on tuner will help you fine tune each string after you get it close with another method. It does not work well when starting from scratch as could be the case if you changed all the strings by taking them all off first or if the guitar was de-tuned for shipping.
If you find yourself in a situation in the future where none of the strings are close to being in tune and you want to tune the guitar from scratch there are several things you can do to get close enough for the clip on tuner to recognize the correct strings.
If you have another guitar that is in tune or a friend's guitar, you can use that as a reference and tune the out of tune guitar to one that is in tune.
If you have a piano, (or other keyboard instrument) you can use the appropriate keys on a piano or keyboard to tune your guitar strings. The keys to use on piano are shown below.
Another option is to use an on line tuning site such as this one: Free Online Guitar tuner Just listen to the pitch on line and adjust your tuning keys until the guitar string you want to tune is close to the sound you hear on the on-line tuner. Then use your clip on tuner to tweak and fine tune it from there.
Another option is to find an app that will play the sounds of a properly tuned guitar the way a pitch pipe would. Some of them have that feature. You would use the same process as an on-line tuning site (compare your string to the sound you hear and adjust until they are close to the same).
Finally, if you are lucky enough to have at least one string close enough for your tuner to pick up, fine tune that string and use that string to get the other strings close using the 5th and 4th fret tuning method described in leftaroundabout's excellent answer. The chart below will help you with this method.
Once you get the strings close enough for your clip on tuner to recognize them properly, use the clip on tuner to make all the final tuning adjustments. Be sure to stretch each string by gently tugging on it and re-tuning until it no longer goes flat when you tug on it.
Good luck on your journey towards learning to play the guitar.