Hola
Gaby_Corr aqui te dejo el mio..
Código HTML:
<script type="text/javascript">
function verifica(){
if(document.form.texto.value!=""){
document.form.button1.disabled=false;
document.form.button2.disabled=false;
document.form.button3.disabled=false;
}else{
document.form.button1.disabled=true;
document.form.button2.disabled=true;
document.form.button3.disabled=true;
}
}
</script>
<form name="form">
<input type="text" name="texto" onblur="verifica()" />
<input type="button" name="button1" value="Consultar" disabled="disabled" />
<input type="button" name="button2" value="Grabar" disabled="disabled" />
<input type="button" name="button3" value="Eliminar" disabled="disabled" />
</form> Espero que te sirva. Saludos@!!