Both parents have rights, regardless of nationality. The problems you'll most likely encounter is the enforcement of those rights and the bias in local enforcement towards the Thai national in mixed couples. Read back over the archives here, and you can find horror stories of farang parents granted full custody, but unable to enforce court orders due to local officials taking no interest.
As the father you're most likely entitled to petition government agencies for information about your daughter. So you may be able to locate her school records this way. This may also assist in locating her.
FWIW my advice is to find one of the larger, more reputable law firms who have Family Law experts, and pay for some initial advice. The reply above, although well-meaning, probably is not going to help your predicament. One thing that the reply mentions that often does come up (and can be leveraged) is money. Taking a transactional approach to this may at least yield information and temporary access. Offer to support your daughter's upkeep. See if this can gain you information/access. Can you contact your wife's family - can they be approached to at least start a dialogue about helping your daughter? Earning some trust with the family may provide dividends down the road.
FWIW I've been through something very similar. It's not easy, but try to keep a positive outlook. Also, take care of yourself and good luck.