I have done upt thrice, ultrasound once,and beta hcg blood test ..all negative ..and it's been 1 month and 7 days ,i had intercourse...all the tests are negative..is there any chance of pregnancy still??

Unlikely: The tests look for hormones created by the tissues of pregnancy that promote/assure the pregnancy continues. Some women just skip a cycle or two occasionally.

Unlikely: Conception occurs within day or so of the sex. It takes about 3 weeks for the embryo to make enough HCG for a positive pregnancy test. Blood test may be done a day after a missed period. Home pregnancy tests should be done 4-5 days after the missed period. If the result is negative repeat the test in 4-5 days. Use first morning urine and follow instructions for the test carefully.