Answer: Based on your description I am not certain what has happened. New tulip bulbs should be planted in the fall so they have ample time to become rooted and undergo their needed chilling period prior to blooming the next spring. Planting too late can delay bloom, for example, and planting inferior quality bulbs or badly undersized bulbs can result in poor bloom.
With tulips, it is not unusual to see some early foliage and then eventually bloom in April/May. Depending on the variety you planted and the microclimate where you planted them, there can be a good six week (or more) difference in blooming times. So it is possible it is still too early for your tulips to bloom and they are actually fine.
If you have the typical mid to late tulips and they have been in the ground for more than a year or two, they may simply have lost the vigor needed to bloom and should be replaced with new bulbs next fall. It is not unusual for older tulips to send up only foliage without blooms and dwindle away over several years time. So if yours are old, they may not bloom and so should be replaced. Plant new bulbs next fall.
If you just planted these last fall and they do not bloom over the coming weeks, and you want to try to save them for next year, do not lift them. This is disruptive and creates extra work for the gardener. It is better to leave them in place and allow them to grow naturally. They need their foliage growth period to build their strength so they can bloom again the following year. Allow the foliage to grow and yellow and dry up naturally before you remove it. You might try an application of general purpose granular fertilizer now and again in mid fall (when they are rooting) to try to give them some extra strength and see if they can bloom next year.
In my experience there are only a few varieties of tulip such as the species or cottage tulips that perform dependably in the garden year after year. These should be left in place and not disturbed, they will last for many years.
I hope this helps.
Q&A Library Searching Tips